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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Med.</journal-id>
<journal-title>Frontiers in Medicine</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Med.</abbrev-journal-title>
<issn pub-type="epub">2296-858X</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/fmed.2024.1499798</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Medicine</subject>
<subj-group>
<subject>Brief Research Report</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Analysis of ASAS health index and its influencing factors in ankylosing spondylitis: a prospective study based on the population of Chaoshan region</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author"><name><surname>Li</surname> <given-names>Aikang</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
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<contrib contrib-type="author"><name><surname>Liang</surname> <given-names>Rongji</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
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<contrib contrib-type="author"><name><surname>Wu</surname> <given-names>Liangbin</given-names></name><xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
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<contrib contrib-type="author"><name><surname>Cai</surname> <given-names>Minghua</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
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<contrib contrib-type="author"><name><surname>Chen</surname> <given-names>Jiayou</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
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<contrib contrib-type="author" corresp="yes"><name><surname>Gong</surname> <given-names>Yao</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref><xref ref-type="aff" rid="aff3"><sup>3</sup></xref><xref ref-type="corresp" rid="c001"><sup>&#x002A;</sup></xref>
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<contrib contrib-type="author" corresp="yes"><name><surname>Zeng</surname> <given-names>Shaoyin</given-names></name><xref ref-type="aff" rid="aff1"><sup>1</sup></xref><xref ref-type="corresp" rid="c001"><sup>&#x002A;</sup></xref>
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<aff id="aff1"><sup>1</sup><institution>Shantou University Medical College</institution>, <addr-line>Shantou</addr-line>, <country>China</country></aff>
<aff id="aff2"><sup>2</sup><institution>Shenzhen University Medical College, Shenzhen University</institution>, <addr-line>Shenzhen</addr-line>, <country>China</country></aff>
<aff id="aff3"><sup>3</sup><institution>First Affiliated Hospital of Shantou University Medical College</institution>, <addr-line>Shantou</addr-line>, <country>China</country></aff>
<author-notes>
<fn fn-type="edited-by" id="fn0001">
<p>Edited by: Ming Yan, Fourth Military Medical University, China</p>
</fn>
<fn fn-type="edited-by" id="fn0002">
<p>Reviewed by: Yiting Lei, Orthopedic Laboratory of Chongqing Medical University, China</p>
<p>Qingxian Li, First Affiliated Hospital of Xiamen University, China</p>
</fn>
<corresp id="c001">&#x002A;Correspondence: Yao Gong, <email>Ygy223@126.com</email>; Shaoyin Zeng, <email>syzeng@stu.edu.cn</email></corresp>
</author-notes>
<pub-date pub-type="epub">
<day>08</day>
<month>01</month>
<year>2025</year>
</pub-date>
<pub-date pub-type="collection">
<year>2024</year>
</pub-date>
<volume>11</volume>
<elocation-id>1499798</elocation-id>
<history>
<date date-type="received">
<day>21</day>
<month>09</month>
<year>2024</year>
</date>
<date date-type="accepted">
<day>24</day>
<month>12</month>
<year>2024</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#x00A9; 2025 Li, Liang, Wu, Cai, Chen, Gong and Zeng.</copyright-statement>
<copyright-year>2025</copyright-year>
<copyright-holder>Li, Liang, Wu, Cai, Chen, Gong and Zeng</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/">
<p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p>
</license>
</permissions>
<abstract>
<sec id="sec1">
<title>Objective</title>
<p>This study aimed to evaluate the health-related quality of life (HRQoL) in ankylosing spondylitis (AS) patients in the Chaoshan region and identify factors influencing the ASAS Health Index (ASAS-HI) to enhance comprehensive AS treatment strategies.</p>
</sec>
<sec id="sec2">
<title>Methods</title>
<p>A survey of ASAS-HI was conducted on 82 AS patients from the rheumatology outpatient department of the First Affiliated Hospital of Shantou University Medical College. The Bath Ankylosing Spondylitis Global Score (BAS-G) assessed overall health status, the Ankylosing Spondylitis Quality of Life Questionnaire (AS-QOL) evaluated quality of life, the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) measured disease activity, and the Bath Ankylosing Spondylitis Functional Index (BASFI) assessed functional difficulties. Inflammatory markers and patient data were collected, and univariate/multivariate logistic regression analyses were used to explore influencing factors of ASAS-HI.</p>
</sec>
<sec id="sec3">
<title>Results</title>
<p>The mean ASAS-HI score was 3.52&#x202F;&#x00B1;&#x202F;3.12. ASAS-HI was positively correlated with BASDAI (<italic>r</italic>&#x202F;=&#x202F;0.478, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.001), ASDAS-CRP (<italic>r</italic>&#x202F;=&#x202F;0.406, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.001), BASFI (<italic>r</italic>&#x202F;=&#x202F;0.338, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.002), and BAS-G (<italic>r</italic>&#x202F;=&#x202F;0.335, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.002). Patients with ASDAS-ES<italic>R</italic> &#x2265;&#x202F;2.1, ASDAS-CRP&#x202F;&#x2265;&#x202F;2.1, and spinal tenderness had significantly higher ASAS-HI scores than others (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.001). Spinal tenderness and radiographic grading were identified as key influencing factors.</p>
</sec>
<sec id="sec4">
<title>Conclusion</title>
<p>ASAS-HI is significantly impacted by disease activity and functional limitations. Early assessment of ASAS-HI is crucial for optimizing disease management in AS patients.</p>
</sec>
</abstract>
<kwd-group>
<kwd>ankylosing spondylitis</kwd>
<kwd>assessment of spondyloarthritis international society health index</kwd>
<kwd>quality of life</kwd>
<kwd>influencing factors</kwd>
<kwd>Chaoshan</kwd>
</kwd-group>
<counts>
<fig-count count="1"/>
<table-count count="5"/>
<equation-count count="0"/>
<ref-count count="52"/>
<page-count count="8"/>
<word-count count="6540"/>
</counts>
<custom-meta-wrap>
<custom-meta>
<meta-name>section-at-acceptance</meta-name>
<meta-value>Geriatric Medicine</meta-value>
</custom-meta>
</custom-meta-wrap>
</article-meta>
</front>
<body>
<sec sec-type="intro" id="sec5">
<label>1</label>
<title>Introduction</title>
<p>Ankylosing spondylitis (AS) is a chronic progressive inflammatory autoimmune disease that affects the sacroiliac joints and the axial skeleton, and sometimes peripheral joints, periarticular tissues, and internal organs. As the disease progresses, deformities and stiffness of the spine can occur (<xref ref-type="bibr" rid="ref1">1</xref>). Young men are the most common population affected by AS. In the Shantou area of Chaoshan, the prevalence of AS is 0.3% (<xref ref-type="bibr" rid="ref2">2</xref>). Symptoms such as low back pain, morning stiffness, and fatigue may appear at the onset of the disease. Additionally, manifestations of enthesitis, such as heel pain, can also occur (<xref ref-type="bibr" rid="ref3">3</xref>). Most patients are at the beginning or peak of their careers, and these symptoms can significantly impact their daily work efficiency and quality of life, leading to loss of social and familial productivity (<xref ref-type="bibr" rid="ref4 ref5 ref6">4&#x2013;6</xref>).</p>
<p>Currently, tools used to assess spondyloarthritis, such as the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS), and other commonly employed scales, primarily focus on specific aspects of health, such as pain, disease activity, and physical function, and are often utilized to evaluate physical performance and health-related quality of life (HR-QoL) (<xref ref-type="bibr" rid="ref7">7</xref>). These tools, which were originally developed based on clinicians&#x2019; experiences with minimal input from patients, primarily measure the direct effects of the disease but fail to comprehensively address broader aspects of patient well-being, including overall quality of life, economic burden, and social relationships. Consequently, the limitations faced by patients with AS in daily activities or fulfilling social role obligations remain inadequately assessed. To overcome these shortcomings, the Assessment of Spondyloarthritis International Society Health Index (ASAS HI) was developed as a more holistic health assessment tool. The ASAS HI is a health index developed for AS patients based on the core set of the International Classification of Functioning, Disability and Health (ICF), aiming to evaluate the actual life status of ankylosing spondylitis patients (<xref ref-type="bibr" rid="ref8">8</xref>, <xref ref-type="bibr" rid="ref9">9</xref>). ASAS HI includes 17 items covering aspects such as pain, emotional function, sleep, sexual function, activity, self-care, community life, and employment. Its reliability and validity have been confirmed (<xref ref-type="bibr" rid="ref10">10</xref>). Therefore, applying ASAS HI for patient assessment can better assess the real-life quality of life of AS patients.</p>
<p>Previous research has demonstrated the strong convergent and discriminative validity of the Assessment of Spondyloarthritis International Society Health Index (ASAS-HI) with established measures such as the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Ankylosing Spondylitis Disease Activity Score-C-Reactive Protein (ASDAS-CRP), highlighting its potential for routine clinical application (<xref ref-type="bibr" rid="ref11">11</xref>). However, few studies have comprehensively evaluated its correlation with patient-reported outcome indicators such as mood disturbances, fatigue, and disease activity in clinical settings. Additionally, the relative importance of certain items in the ASAS-HI, such as using the toilet, driving, and hair washing, varies significantly between geographical regions due to cultural differences. Therefore, this study aims to explore the quality of life and influencing factors of AS patients in the Chaoshan region. By conducting multiple regression analysis on the correlations between various assessment tools, patient examinations, laboratory tests, and the ASAS-HI, the study seeks to provide guidance for developing personalized comprehensive treatment plans.</p>
</sec>
<sec sec-type="methods" id="sec6">
<label>2</label>
<title>Methods</title>
<sec id="sec7">
<label>2.1</label>
<title>Subjects and inclusion criteria</title>
<p>This cross-sectional study included 82 AS patients recruited from the rheumatology outpatient department of the First Affiliated Hospital of Shantou University Medical College from July 2019 to January 2020 as observation and follow-up subjects. Inclusion criteria: (1) Patients who meet the revised New York criteria for AS diagnosis in 1984 (<xref ref-type="bibr" rid="ref12">12</xref>), and all patients were diagnosed with AS by medical history and imaging examination; (2) Patients who are informed about the content and purpose of this study and sign an informed consent form. Exclusion criteria: (1) Patients with concomitant severe cardiac, hepatic, renal, or other important organ and blood, endocrine system lesions or history; (2) Patients who cannot cooperate to complete the self-assessment questionnaire and relevant examinations due to mental abnormalities or any other reasons.</p>
</sec>
<sec id="sec8">
<label>2.2</label>
<title>Study design</title>
<sec id="sec9">
<label>2.2.1</label>
<title>Socio-demographic characteristics</title>
<p>Record general patient information, including name, gender, age, marital status, occupation, education level, dietary habits, alcohol and tobacco use, and religious beliefs.</p>
</sec>
<sec id="sec10">
<label>2.2.2</label>
<title>ASAS hi</title>
<p>It includes 17 domains covering pain, maintaining a body position, moving around, toileting, energy and drive, motivation, sexual functions, driving, community life, handing stress, recreation and leisure, emotional functions, washing oneself, economic self-sufficiency, sleep, and handling stress. Patients self-assess each domain by selecting &#x201C;agree,&#x201D; &#x201C;disagree,&#x201D; or &#x201C;not applicable.&#x201D; A score of 1 is assigned for each domain marked as &#x201C;agree,&#x201D; with a total score calculated from the 17 domains. A score of 0 represents the best outcome, while 17 represents the worst (<xref ref-type="bibr" rid="ref13">13</xref>).</p>
</sec>
<sec id="sec11">
<label>2.2.3</label>
<title>Disease assessment</title>
<p>
<list list-type="order">
<list-item>
<p>Bath Ankylosing Spondylitis Global Score (BAS-G) (<xref ref-type="bibr" rid="ref14">14</xref>): This assesses the overall condition of AS through a self-administered questionnaire, consisting of two questions. Patients are asked to mark their overall estimation of their condition over the past week and the past 6 months on a 10&#x202F;cm visual analogue scale (VAS).</p>
</list-item>
<list-item>
<p>Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) (<xref ref-type="bibr" rid="ref15">15</xref>): Comprising six questions related to symptoms of fatigue, spinal pain, joint tenderness, local tenderness, and morning stiffness, BASDAI assesses patients&#x2019; scores for each question using a VAS. The average score is calculated, with a total range of 0&#x2013;10 points, where 0 indicates the best and 10 indicates the worst.</p>
</list-item>
<list-item>
<p>Bath Ankylosing Spondylitis Functional Index (BASFI) (<xref ref-type="bibr" rid="ref15">15</xref>): Based on prompts for the following 10 activities, patients are asked to mark the difficulty of completing these activities on a scale. The activities include putting on socks or close-fitting clothes, bending to pick up objects, reaching for items from a higher place, standing up from a chair without armrests, getting up from lying on the floor, standing for 10&#x202F;min without discomfort, climbing 10&#x2013;15 steps, looking backward, engaging in physical activities, and completing a day of household and work tasks. The average score is calculated, with 0 indicating the best and 10 indicating the worst.</p>
</list-item>
<list-item>
<p>C-reactive protein (CRP) levels were measured by fully automated dry chemistry method: normal range 0&#x2013;10&#x202F;mg/L; Erythrocyte sedimentation rate (ESR) was measured by fully automated erythrocyte sedimentation rate analyzer: normal range 0&#x2013;15&#x202F;mm/h; Ankylosing Spondylitis Disease Activity Score (ASDAS)-CRP (<xref ref-type="bibr" rid="ref16">16</xref>): ASDAS-CRP&#x202F;=&#x202F;0.121&#x202F;&#x00D7;&#x202F;back pain score&#x202F;+&#x202F;0.058&#x202F;&#x00D7;&#x202F;morning stiffness duration score&#x202F;+&#x202F;0.11&#x202F;&#x00D7;&#x202F;patient global score&#x202F;+&#x202F;0.073&#x202F;&#x00D7;&#x202F;peripheral joint pain &#x00F7; swelling 1score&#x202F;+&#x202F;0.579&#x202F;&#x00D7;&#x202F;ln(CRP&#x202F;+&#x202F;1); Ankylosing Spondylitis Disease Activity Score (ASDAS)-ESR (<xref ref-type="bibr" rid="ref17">17</xref>): ASDAS-ES<italic>R</italic> =&#x202F;0.079&#x202F;&#x00D7;&#x202F;back pain score&#x202F;+&#x202F;0.069&#x202F;&#x00D7;&#x202F;morning stiffness duration score&#x202F;+&#x202F;0.113&#x202F;&#x00D7;&#x202F;patient global score&#x202F;+&#x202F;0.086&#x202F;&#x00D7;&#x202F;peripheral joint pain &#x00F7; swelling score&#x202F;+&#x202F;0.293&#x202F;&#x00D7;&#x202F;&#x221A;ESR.</p>
</list-item>
</list>
</p>
</sec>
<sec id="sec12">
<label>2.2.4</label>
<title>Skeletal and muscular system activity assessment</title>
<p>
<list list-type="order">
<list-item>
<p>Chest expansion (cm) (<xref ref-type="bibr" rid="ref18">18</xref>): Standing upright, measure the horizontal distance between the fourth ribs using a scaled soft ruler, with the difference between maximum inspiration and maximum expiration. A difference of &#x003C;2.5&#x202F;cm is considered abnormal.</p>
</list-item>
<list-item>
<p>Schober&#x2019;s test (cm) (<xref ref-type="bibr" rid="ref19">19</xref>): Mark a point 10&#x202F;cm above the midpoint of the line connecting the posterior superior iliac spines, then ask the patient to bend forward (while keeping both knees straight) to measure the maximum flexion of the spine. Normal mobility increases the distance by more than 5&#x202F;cm, while those with spinal involvement increase the distance by less than 4&#x202F;cm.</p>
</list-item>
<list-item>
<p>Finger-to-ground distance (cm) (<xref ref-type="bibr" rid="ref20">20</xref>): Standing upright with legs and knees extended, bend forward, and move the index finger downwards along a vertical ruler placed in front of the foot. The distance from the ground is measured as the finger-to-ground distance.</p>
</list-item>
<list-item>
<p>Spinal mobility (degrees) (<xref ref-type="bibr" rid="ref21">21</xref>): Includes lumbar spine flexion, extension, left lateral flexion, and right lateral flexion. Normal flexion is 45 degrees, extension is 35 degrees, and lateral flexion is 30 degrees on each side.</p>
</list-item>
<list-item>
<p>Spinal tenderness (<xref ref-type="bibr" rid="ref22">22</xref>): The examinee adopts a seated position with slight forward bending. The examiner uses the thumb or index finger pad to sequentially press down from top to bottom on the spinous and transverse processes of the spine, as well as the paravertebral muscles. Normal findings should not produce tenderness.</p>
</list-item>
<list-item>
<p>Patrick&#x2019;s test (Lower limb &#x201C;4-letter test&#x201D;) (<xref ref-type="bibr" rid="ref23">23</xref>): The patient lies supine, with one knee flexed and the heel placed on the opposite extended knee. The examiner presses down on the flexed knee with one hand (while the hip joint is flexed, abducted, and externally rotated), while applying pressure to the opposite hip with the other hand. Pain in the contralateral sacroiliac joint is considered positive.</p>
</list-item>
</list>
</p>
</sec>
<sec id="sec13">
<label>2.2.5</label>
<title>Imaging index detection</title>
<p>The degree of sacroiliitis on X-ray is classified into 5 levels: Grade 0: Normal; Grade I: Suspicious (roughness of joint surface, small cystic changes, slight sclerosis); Grade II: Definite joint surface erosion, no significant change in joint space; Grade III: Severe joint surface erosion or secondary repair leading to pseudo-widening or narrowing of joint space, local fusion; Grade IV: Bilateral sacroiliac joint surface fusion (<xref ref-type="bibr" rid="ref24">24</xref>). Diagnostic criteria for ankylosing spondylitis on imaging (<xref ref-type="bibr" rid="ref25">25</xref>): Bilateral sacroiliitis Grade&#x202F;&#x2265;&#x202F;II, or unilateral sacroiliitis Grade III-IV (<xref ref-type="fig" rid="fig1">Figure 1</xref>).</p>
<fig position="float" id="fig1">
<label>Figure 1</label>
<caption>
<p>The degree of sacroiliitis on X-ray. <bold>(A)</bold> Grade I: Suspicious (joint surface roughness, small cystic changes, slight sclerosis); <bold>(B)</bold> Grade II: Definite joint surface erosion without significant joint space changes; <bold>(C)</bold> Grade III: Severe joint surface erosion, pseudo-widening/narrowing of joint space, or partial fusion; <bold>(D)</bold> Grade IV: Bilateral sacroiliac joint fusion.</p>
</caption>
<graphic xlink:href="fmed-11-1499798-g001.tif"/>
</fig>
</sec>
</sec>
<sec id="sec14">
<label>2.3</label>
<title>Statistical analysis</title>
<p>Statistical analysis was performed using SPSS 20.0 software. Descriptive analysis was used for general data. Independent sample <italic>t</italic>-test was conducted to analyze whether there were differences in means between two groups, with results presented as mean&#x202F;&#x00B1;&#x202F;standard deviation. Spearman correlation coefficient was calculated to assess the correlation between ASAS HI and other relevant disease indicators. Linear regression analysis was employed to identify predictors of ASAS HI. A <italic>p</italic>-value &#x003C;0.05 was considered statistically significant.</p>
</sec>
</sec>
<sec sec-type="results" id="sec15">
<label>3</label>
<title>Results</title>
<sec id="sec16">
<label>3.1</label>
<title>Baseline characteristics</title>
<p>This study included 82 AS patients who met the inclusion criteria. Among these patients, 64 were male (78.0%) and 18 were female (22.0%), with a mean age of 32.0&#x202F;&#x00B1;&#x202F;11.3&#x202F;years (range: 16&#x2013;65&#x202F;years). Educational attainment varied: 47 patients (57.3%) had a junior high school education or below, 8 patients (9.8%) had a high school education, and 27 patients (32.9%) had a college education or higher. Employment status revealed that 75 patients (91.5%) were employed, whereas 7 (8.5%) were unemployed. Marital status was nearly evenly distributed, with 40 patients (48.8%) being married and 42 (51.2%) unmarried. The average disease duration was 10.3&#x202F;&#x00B1;&#x202F;7.1&#x202F;years. Additionally, 70 cases (85.4%) tested positive for the HLA-B27 gene, while 12 cases (14.6%) tested negative (<xref ref-type="table" rid="tab1">Table 1</xref>).</p>
<table-wrap position="float" id="tab1">
<label>Table 1</label>
<caption>
<p>General characteristics of ankylosing spondylitis patients.</p>
</caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th align="left" valign="top">Item</th>
<th/>
<th align="center" valign="top" colspan="2">Data (<italic>N</italic>&#x202F;=&#x202F;82)</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="middle">Age, years [Mean (SD)]</td>
<td/>
<td align="center" valign="middle" colspan="2">32.0&#x202F;&#x00B1;&#x202F;11.3</td>
</tr>
<tr>
<td align="left" valign="middle">Disease duration, years [Mean (SD)]</td>
<td/>
<td align="center" valign="middle" colspan="2">10.3&#x202F;&#x00B1;&#x202F;7.1</td>
</tr>
<tr>
<td align="left" valign="middle" rowspan="2">Sex (<italic>n</italic>, %)</td>
<td align="left" valign="middle">Male</td>
<td align="center" valign="middle">64</td>
<td align="center" valign="middle">78.0%</td>
</tr>
<tr>
<td align="left" valign="middle">Female</td>
<td align="center" valign="middle">18</td>
<td align="center" valign="middle">22.0%</td>
</tr>
<tr>
<td align="left" valign="middle" rowspan="3">Education (<italic>n</italic>, %)</td>
<td align="left" valign="middle">Middle school or less</td>
<td align="center" valign="middle">47</td>
<td align="center" valign="middle">57.3%</td>
</tr>
<tr>
<td align="left" valign="middle">High school</td>
<td align="center" valign="middle">8</td>
<td align="center" valign="middle">9.6%</td>
</tr>
<tr>
<td align="left" valign="middle">College or more</td>
<td align="center" valign="middle">27</td>
<td align="center" valign="middle">32.9%</td>
</tr>
<tr>
<td align="left" valign="middle" rowspan="2">Marital status (<italic>n</italic>, %)</td>
<td align="left" valign="middle">Single</td>
<td align="center" valign="middle">42</td>
<td align="center" valign="middle">51.2%</td>
</tr>
<tr>
<td align="left" valign="middle">Married</td>
<td align="center" valign="middle">40</td>
<td align="center" valign="middle">48.8%</td>
</tr>
<tr>
<td align="left" valign="middle" rowspan="2">Employment status (<italic>n</italic>, %)</td>
<td align="left" valign="middle">Employment</td>
<td align="center" valign="middle">75</td>
<td align="center" valign="middle">91.5%</td>
</tr>
<tr>
<td align="left" valign="middle">Unemployed</td>
<td align="center" valign="middle">7</td>
<td align="center" valign="middle">8.5%</td>
</tr>
<tr>
<td align="left" valign="middle" rowspan="2">HLA-B27 (<italic>n</italic>, %)</td>
<td align="left" valign="middle">Positive</td>
<td align="center" valign="middle">70</td>
<td align="center" valign="middle">85.4%</td>
</tr>
<tr>
<td align="left" valign="middle">Negative</td>
<td align="center" valign="middle">12</td>
<td align="center" valign="middle">14.6%</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<p>SD, standard deviation; HLA-B27, human leukocyte antigen-B27.</p>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="sec17">
<label>3.2</label>
<title>Comparison of ASAS HI scores according to disease activity status</title>
<p>ASAS HI score was 3.52&#x202F;&#x00B1;&#x202F;3.12 (0&#x2013;17). Scores of 0&#x2013;5 were considered good in 60 cases (73.2%); 6&#x2013;12 were considered moderate in 21 cases (25.6%); and 13&#x2013;17 were considered poor in 1 case (1.2%). ASDAS has well-validated cutoff values, with ASDAS &#x003C;2.1 indicating low disease activity and ASDAS &#x2265;2.1 indicating high disease activity. ASAS HI scores were significantly higher in patients with ASDAS-CRP &#x2265;2.1 (5.21&#x202F;&#x00B1;&#x202F;3.52) compared to ASDAS-CRP &#x003C;2.1 (2.65&#x202F;&#x00B1;&#x202F;2.45) (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.001); ASAS HI scores were also significantly higher in patients with ASDAS-ESR &#x2265;2.1 (5.32&#x202F;&#x00B1;&#x202F;3.80) compared to ASDAS-CRP &#x003C;2.1 (2.59&#x202F;&#x00B1;&#x202F;2.21) (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.001); ASAS HI scores in patients with spinal tenderness (5.58&#x202F;&#x00B1;&#x202F;3.52) were significantly higher than those without tenderness (2.90&#x202F;&#x00B1;&#x202F;2.72) (<xref ref-type="table" rid="tab2">Table 2</xref>).</p>
<table-wrap position="float" id="tab2">
<label>Table 2</label>
<caption>
<p>Comparing ASAS HI scores among different disease activity States (<italic>n</italic>&#x202F;=&#x202F;82).</p>
</caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th/>
<th align="center" valign="top" colspan="2">ASDAS-CRP</th>
<th align="center" valign="top" colspan="2">ASDAS-ESR</th>
<th align="center" valign="top" colspan="2">BASDAI</th>
<th align="center" valign="top" colspan="2">Spinal tenderness</th>
</tr>
<tr>
<th align="left" valign="top">Grade</th>
<th align="center" valign="top">&#x003C;2.1</th>
<th align="center" valign="top">&#x2265;2.1</th>
<th align="center" valign="top">&#x003C;2.1</th>
<th align="center" valign="top">&#x2265;2.1</th>
<th align="center" valign="top">&#x003C;4</th>
<th align="center" valign="top">&#x2265;4</th>
<th align="center" valign="top">Negative</th>
<th align="center" valign="top">Positive</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="middle">HI (X&#x202F;&#x00B1;&#x202F;S)</td>
<td align="center" valign="middle">2.65&#x202F;&#x00B1;&#x202F;2.45</td>
<td align="center" valign="middle">5.21&#x202F;&#x00B1;&#x202F;3.52</td>
<td align="center" valign="middle">2.59&#x202F;&#x00B1;&#x202F;2.21</td>
<td align="center" valign="middle">5.32&#x202F;&#x00B1;&#x202F;3.80</td>
<td align="center" valign="middle">3.22&#x202F;&#x00B1;&#x202F;2.87</td>
<td align="center" valign="middle">4.87&#x202F;&#x00B1;&#x202F;3.89</td>
<td align="center" valign="middle">2.90&#x202F;&#x00B1;&#x202F;2.72</td>
<td align="center" valign="middle">5.58&#x202F;&#x00B1;&#x202F;3.52</td>
</tr>
<tr>
<td align="left" valign="middle"><italic>n</italic></td>
<td align="center" valign="middle">54 (65.9%)</td>
<td align="center" valign="middle">28 (34.1%)</td>
<td align="center" valign="middle">54 (65.9%)</td>
<td align="center" valign="middle">28 (34.1%)</td>
<td align="center" valign="middle">67 (81.7%)</td>
<td align="center" valign="middle">15 (18.3%)</td>
<td align="center" valign="middle">63 (76.8%)</td>
<td align="center" valign="middle">19 (23.2%)</td>
</tr>
<tr>
<td align="left" valign="middle"><italic>P</italic></td>
<td align="center" valign="middle" colspan="2">&#x003C;0.001</td>
<td align="center" valign="middle" colspan="2">&#x003C;0.001</td>
<td align="center" valign="middle" colspan="2">&#x003E;0.05</td>
<td align="center" valign="middle" colspan="2">&#x003C;0.001</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<p>ASDAS-CRP, ankylosing spondylitis disease activity score - C-reactive protein; ASDAS-ESR, Ankylosing spondylitis disease activity score - erythrocyte sedimentation rate; BASDAI, bath ankylosing spondylitis disease activity index.</p>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="sec18">
<label>3.3</label>
<title>Correlation of ASAS HI with disease activity and musculoskeletal function</title>
<p>ASAS HI showed a strong correlation with BASDAI (<italic>r</italic> =&#x202F;0.478, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.001). Additionally, ASAS HI was positively correlated with ASDAS-CRP (<italic>r</italic> =&#x202F;0.406, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.001), pain (<italic>r</italic> =&#x202F;0.369, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.001), BASFI (<italic>r</italic> =&#x202F;0.338, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.002), BAS-G (<italic>r</italic> =&#x202F;0.335, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.002), ASDAS-ESR (<italic>r</italic> =&#x202F;0.331, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.002), and fingertip-to-floor distance (<italic>r</italic> =&#x202F;0.273, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.013). No correlation was found between ASAS HI and chest expansion or Schober test (<italic>p</italic>&#x202F;&#x003E;&#x202F;0.05) (<xref ref-type="table" rid="tab3">Table 3</xref>).</p>
<table-wrap position="float" id="tab3">
<label>Table 3</label>
<caption>
<p>Correlation between ASAS HI and disease activity and musculoskeletal activity.</p>
</caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th/>
<th align="center" valign="top">ASDAS-CRP</th>
<th align="center" valign="top">ASDAS-ESR</th>
<th align="center" valign="top">BAS-G</th>
<th align="center" valign="top">BASDAI</th>
<th align="center" valign="top">BASFI</th>
<th align="center" valign="top">Pain</th>
<th align="center" valign="top">Finger-to-floor distance</th>
<th align="center" valign="top">Chest expansion</th>
<th align="center" valign="top">Schober&#x2019;s test</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="middle"><italic>r</italic></td>
<td align="center" valign="middle">0.406</td>
<td align="center" valign="middle">0.331</td>
<td align="center" valign="middle">0.335</td>
<td align="center" valign="middle">0.478</td>
<td align="center" valign="middle">0.338</td>
<td align="center" valign="middle">0.369</td>
<td align="center" valign="middle">0.273</td>
<td align="center" valign="middle">0.001</td>
<td align="center" valign="middle">0.052</td>
</tr>
<tr>
<td align="left" valign="middle"><italic>P</italic></td>
<td align="center" valign="middle">&#x003C;0.001</td>
<td align="center" valign="middle">&#x003C;0.002</td>
<td align="center" valign="middle">&#x003C;0.002</td>
<td align="center" valign="middle">&#x003C;0.001</td>
<td align="center" valign="middle">&#x003C;0.002</td>
<td align="center" valign="middle">&#x003C;0.001</td>
<td align="center" valign="middle">&#x003C;0.013</td>
<td align="center" valign="middle">&#x003E;0.05</td>
<td align="center" valign="middle">&#x003E;0.05</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<p>ASDAS-CRP, ankylosing spondylitis disease activity score based on C-reactive protein; ASDAS-ESR, ankylosing spondylitis disease activity score based on erythrocyte sedimentation rate; BAS-G, bath ankylosing spondylitis global score; BASDAI, bath ankylosing spondylitis disease activity index; BASFI, bath ankylosing spondylitis functional index.</p>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="sec19">
<label>3.4</label>
<title>Correlation between ASAS HI and radiographic grading</title>
<p>Bilateral sacroiliitis grade II was observed in 38 cases (46.3%), grade III in 29 cases (35.4%), and grade IV in 15 cases (18.3%). The ASAS HI for grade II bilateral sacroiliitis was 2.39&#x202F;&#x00B1;&#x202F;2.62; for grade III, it was 4.48&#x202F;&#x00B1;&#x202F;3.26 on average; and for grade IV, it was 4.53&#x202F;&#x00B1;&#x202F;3.23. There was a weak correlation between ASAS HI and radiographic grading (<italic>r</italic> =&#x202F;0.281, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.002) (<xref ref-type="table" rid="tab4">Table 4</xref>).</p>
<table-wrap position="float" id="tab4">
<label>Table 4</label>
<caption>
<p>The correlation between ASAS HI and radiographic grade.</p>
</caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th rowspan="2"/>
<th align="center" valign="top" colspan="3">Radiographic grade</th>
</tr>
<tr>
<th align="center" valign="top">II</th>
<th align="center" valign="top">III</th>
<th align="center" valign="top">IV</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="middle"><italic>n</italic></td>
<td align="center" valign="middle">38</td>
<td align="center" valign="middle">29</td>
<td align="center" valign="middle">15</td>
</tr>
<tr>
<td align="left" valign="middle">HI (<sup>&#x2212;</sup>X&#x202F;&#x00B1;&#x202F;S)</td>
<td align="center" valign="middle">2.39&#x202F;&#x00B1;&#x202F;2.62</td>
<td align="center" valign="middle">4.48&#x202F;&#x00B1;&#x202F;3.256</td>
<td align="center" valign="middle">4.53&#x202F;&#x00B1;&#x202F;3.23</td>
</tr>
<tr>
<td align="left" valign="middle"><italic>r</italic></td>
<td align="center" valign="middle" colspan="3">0.281</td>
</tr>
<tr>
<td align="left" valign="middle"><italic>P</italic></td>
<td align="center" valign="middle" colspan="3">&#x003C;0.002</td>
</tr>
</tbody>
</table>
</table-wrap>
</sec>
<sec id="sec20">
<label>3.5</label>
<title>Multiple linear regression analysis</title>
<p>Multiple linear regression was used to predict ASAS HI based on BAS-G, BASDAI, BASFI, ASDAS-CRP, ASDAS-ESR, and radiographic grading. The results showed that spinal tenderness and radiographic grading of sacroiliitis were positively correlated with ASAS HI (<italic>&#x03B2;</italic>&#x202F;=&#x202F;1.828, <italic>p</italic>&#x202F;=&#x202F;0.027; <italic>&#x03B2;</italic>&#x202F;=&#x202F;0.957, <italic>p</italic>&#x202F;=&#x202F;0.029). The regression model was statistically significant, <italic>F</italic>&#x202F;=&#x202F;5.238, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.001, adjusted <italic>R</italic><sup>2</sup>&#x202F;=&#x202F;0.239. Spinal tenderness and radiographic grading were the main influencing factors of ASAS HI (<xref ref-type="table" rid="tab5">Table 5</xref>).</p>
<table-wrap position="float" id="tab5">
<label>Table 5</label>
<caption>
<p>Linear regression of factors influencing ASAS HI.</p>
</caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th/>
<th align="center" valign="top">
<italic>&#x03B2;</italic>
</th>
<th align="center" valign="top">SE</th>
<th align="center" valign="top">
<italic>p</italic>
</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="middle">ASDAS-CRP</td>
<td align="left" valign="middle">0.568</td>
<td align="center" valign="middle">0.772</td>
<td align="center" valign="middle">0.464</td>
</tr>
<tr>
<td align="left" valign="middle">ASDAS-ESR</td>
<td align="left" valign="middle">&#x2212;0.799</td>
<td align="center" valign="middle">0.764</td>
<td align="center" valign="middle">0.299</td>
</tr>
<tr>
<td align="left" valign="middle">BAS-G</td>
<td align="left" valign="middle">0.033</td>
<td align="center" valign="middle">0.214</td>
<td align="center" valign="middle">0.877</td>
</tr>
<tr>
<td align="left" valign="middle">BASDAI</td>
<td align="left" valign="middle">0.474</td>
<td align="center" valign="middle">0.447</td>
<td align="center" valign="middle">0.293</td>
</tr>
<tr>
<td align="left" valign="middle">BASFI</td>
<td align="left" valign="middle">0.368</td>
<td align="center" valign="middle">0.274</td>
<td align="center" valign="middle">0.184</td>
</tr>
<tr>
<td align="left" valign="middle">Pain</td>
<td align="left" valign="middle">&#x2212;0.021</td>
<td align="center" valign="middle">0.227</td>
<td align="center" valign="middle">0.927</td>
</tr>
<tr>
<td align="left" valign="middle">Finger-to-floor distance</td>
<td align="left" valign="middle">0.015</td>
<td align="center" valign="middle">0.029</td>
<td align="center" valign="middle">0.599</td>
</tr>
<tr>
<td align="left" valign="middle">Spinal tenderness</td>
<td align="left" valign="middle">1.828</td>
<td align="center" valign="middle">0.812</td>
<td align="center" valign="middle">0.027</td>
</tr>
<tr>
<td align="left" valign="middle">Radiographic grade</td>
<td align="left" valign="middle">0.957</td>
<td align="center" valign="middle">0.429</td>
<td align="center" valign="middle">0.029</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<p>ASDAS-CRP, ankylosing spondylitis disease activity score based on C-reactive protein; ASDAS-ESR, ankylosing spondylitis disease activity score based on erythrocyte sedimentation rate; BAS-G, bath ankylosing spondylitis global score; BASDAI, bath ankylosing spondylitis disease activity index; BASFI, bath ankylosing spondylitis functional index.</p>
</table-wrap-foot>
</table-wrap>
</sec>
</sec>
<sec sec-type="discussion" id="sec21">
<label>4</label>
<title>Discussion</title>
<p>Previous studies have shown that chronic diseases are one of the most important factors affecting the quality of life of Chinese residents (<xref ref-type="bibr" rid="ref26">26</xref>). AS, as a major chronic inflammatory rheumatic disease affecting young adults, is characterized by recurrent pain, fatigue, and functional impairment (<xref ref-type="bibr" rid="ref27">27</xref>); as the disease progresses, the entire spine can become rigid from bottom to top, with late-stage manifestations including hip stiffness, severe spinal deformity, and kyphosis, which can lead to disability and impose significant pressure on patients and their families, severely affecting patients&#x2019; quality of life (<xref ref-type="bibr" rid="ref28">28</xref>). The selection of items for the ASAS Health Index (HI) was conducted collaboratively among rheumatologists, healthcare professionals, and patients with AS from a core set of ICF variables. This process underscores the ASAS HI serves as a practical assessment of patients&#x2019; actual discomfort in daily life. Assessing the quality of life and social functioning of patients with chronic diseases can provide a basis for improving treatment strategies and evaluating treatment outcomes, as well as facilitating health education for patients, improving prognosis, and reducing the degree of social function impairment in patients (<xref ref-type="bibr" rid="ref29">29</xref>). However, the factors influencing ASAS HI have not been clearly demonstrated so far. In the present study, we determined ASAS HI prospectively in a single cohort and identified several factors including various assessment tools and data from physical examinations, laboratory tests and imaging that are associated with ASAS HI. BASFI, BAS-G, ASDAS-CRP, ASDAS-ESR, fingertip-to-floor distance, hip joint pain severity, spinal tenderness, and radiographic grading of sacroiliitis were found to be correlated with HI scores.</p>
<sec id="sec22">
<label>4.1</label>
<title>The impact of functionality and ability on the quality of life of AS patients</title>
<p>The BASFI scale, developed for defining and monitoring functional capabilities in individuals with AS (<xref ref-type="bibr" rid="ref30">30</xref>), is commonly applied in clinical practice to predict patients&#x2019; work performance and everyday functioning (<xref ref-type="bibr" rid="ref31">31</xref>). In a recent study, Imke Redeker et al. demonstrated that physical function significantly influences the ASAS Health Index (HI) through a Bayesian network analysis that integrates expert knowledge and observational data (<xref ref-type="bibr" rid="ref32">32</xref>). The BAS-G is a patient-centered assessment tool that provides a comprehensive insight into the impact of ankylosing spondylitis (<xref ref-type="bibr" rid="ref33">33</xref>). Our study revealed a positive correlation between patients&#x2019; quality-of-life HI scores and their BASFI scores for ability and function (<italic>r</italic> =&#x202F;0.338), consistent with previous research (<xref ref-type="bibr" rid="ref34">34</xref>), as well as with their overall condition as measured by the BAS-G scale (<italic>r</italic> =&#x202F;0.335). This indicates that patients&#x2019; susceptibility to fatigue, ability to engage in physical activities, and performance in daily functions significantly influence their quality of life. Furthermore, the diminished quality of life exacerbates patients&#x2019; discomfort with their current physical condition. However, the relatively low correlation coefficient (<xref ref-type="bibr" rid="ref35">35</xref>) may be attributed to the fact that both the BAS-G and BASFI rely predominantly on the subjective evaluations of patients,which potentially limits the precision and reproducibility of the results. Fatigue has been shown to be one of the most significant factors affecting patients&#x2019; well-being (<xref ref-type="bibr" rid="ref14">14</xref>). Adding direct fatigue measurement tools, such as the Fatigue Severity Scale, may provide deeper insights into the potential fatigue factors reflected in BASFI and BAS-G scores. This approach could help align quality-of-life assessments with disease management strategies more effectively. As an important non-pharmacological treatment for AS, rehabilitation exercises can effectively improve the life and work ability of patients. A meta-analysis reveals that various forms of exercise, including home-based exercise programs, swimming, Pilates training, and supervised exercises, have a positive effect on the BASFI across all selected studies. Furthermore, no heterogeneity was observed in the reduction of BASFI [&#x2212;0.72 (&#x2212;1.03; &#x2212;0.40)] and the reduction of trials involving anti-TNF therapy [&#x2212;0.81 (&#x2212;1.25; &#x2212;0.38)], thereby reinforcing the potential of exercise programs to improve physical function in patients with AS (<xref ref-type="bibr" rid="ref36">36</xref>). Patients need to consciously engage in muscle strength exercises, spinal flexibility exercises, chest expansion exercises, etc., in their daily lives, and avoid joint-impact, explosive, and high-load exercises. They can participate in swimming, yoga, tai chi, and other sports (<xref ref-type="bibr" rid="ref37">37</xref>, <xref ref-type="bibr" rid="ref38">38</xref>). However, most patients lack sufficient understanding of AS-related knowledge, do not understand the importance of functional exercise in preventing spinal dysfunction, and often have poor compliance with rehabilitation treatment. How to promote the widespread adoption of rehabilitation exercises, which are effective and simple, is worth further research.</p>
</sec>
<sec id="sec23">
<label>4.2</label>
<title>The impact of disease activity on the quality of life of AS patients</title>
<p>Among the proposed indices to evaluate disease activity of AS, BASDAI is currently the most widely used in clinical trials and in daily practice as yet (<xref ref-type="bibr" rid="ref39">39</xref>, <xref ref-type="bibr" rid="ref40">40</xref>). However, the BASDAI scale can present ambiguities in assessing disease activity due to its dependence on patients&#x2019; subjective self-assessment, which introduces certain limitations in its clinical use (<xref ref-type="bibr" rid="ref41">41</xref>). In order to more systematically and objectively evaluate the disease activity of patients, this study introduced the Ankylosing Spondylitis Disease Activity Score (ASDAS) that reflects several aspects of disease activity and shows a strong correlation with both physician and patient assessments of the condition, including both ASDAS-CRP and ASDAS-ESR indices. ASDAS is advocated as the primary tool for assessing disease activity in axSpA. The 2022 ASAS-EULAR management update for axSpA highlights that the main objective of treatment is to optimize health-related quality of life by managing symptoms and inflammation, preventing further structural damage, and maintaining or restoring function and social participation (<xref ref-type="bibr" rid="ref42">42</xref>). The analysis revealed that there was a certain correlation between the Health Index (HI) and BASDAI (<italic>r</italic> =&#x202F;0.478), ASDAS-ESR (<italic>r</italic> =&#x202F;0.331), and ASDAS-CRP (<italic>r</italic> =&#x202F;0.406). Groups with higher disease activity showed greater mean ASAS HI scores compared to those with lower activity, suggesting that ASAS-HI effectively differentiates disease activity levels, a key factor in evaluating its clinical relevance. Furthermore, HI was positively correlated with the degree of lumbar, back, and hip joint pain (<italic>r</italic> =&#x202F;0.369), as well as spinal tenderness and other disease activity indicators. Pain is one of the most direct effects of AS, results from either inflammation or neuropathic mechanisms (<xref ref-type="bibr" rid="ref43">43</xref>).It significantly affects patients&#x2019; daily activities and contributes to a decline in quality of life. The clinical characteristics of AS include a long course, prolonged medication duration, and recurrent disease episodes, necessitating correct and regular medication and rehabilitation training to reduce disease activity (<xref ref-type="bibr" rid="ref44">44</xref>). However, due to the long duration of drug use, severe adverse reactions, and high treatment costs, patients often have poor compliance, resulting in frequent disease activity, worsening condition, and affecting their quality of life. Therefore, in order to improve patient compliance, medical staff need to understand the patients&#x2019; economic conditions and daily lives, and adopt the most effective, least adverse reactions, and patient-friendly treatment plans. On the other hand, patients also need to follow the doctor&#x2019;s arrangements, and family members should provide sufficient care to ensure that patients receive comprehensive support and care, in order to improve treatment compliance and quality of life. Besides, the difference in BASDI scores was not statistically significant, which may be related to the smaller number of patients with disease activity (BASDI&#x2265;4), and further investigation is needed to expand the sample size.</p>
</sec>
<sec id="sec24">
<label>4.3</label>
<title>The relationship between spinal mobility and HI scores</title>
<p>The characteristic feature of AS is the gradual onset of sacroiliitis and fibrosis as well as ossification of various joints of the spine (<xref ref-type="bibr" rid="ref45">45</xref>), with sacroiliac joints often being the first affected (<xref ref-type="bibr" rid="ref46">46</xref>). As the condition progresses, the lesions continue to accumulate upward involving the lumbar, thoracic, and cervical vertebrae, eventually leading to spinal stiffness in the late stage (<xref ref-type="bibr" rid="ref47">47</xref>). Stiffness, included in the ASAS core domains for assessment, contributes to pain, functional impairment, and reduced quality of life (<xref ref-type="bibr" rid="ref48">48</xref>). This study utilized the Schober test, finger-to-floor distance, and chest expansion to measure spinal mobility in AS patients. The results showed a weak correlation between HI score and finger-to-floor distance (<italic>r</italic> =&#x202F;0.273), while there was no statistically significant association with Schober test or chest expansion. Furthermore, the radiographic grading of sacroiliitis can reflect the severity of sacroiliac joint involvement, with more severe involvement leading to poorer mobility of the sacroiliac joints. HI score exhibited a weak correlation with the radiographic grading of sacroiliitis (<italic>r</italic> =&#x202F;0.281), indicating that higher grading was associated with higher HI scores. Some studies (<xref ref-type="bibr" rid="ref49 ref50 ref51">49&#x2013;51</xref>) have shown that spinal mobility can affect the quality of life of patients, and there may be discrepancies with the results of this experiment, possibly due to the focus of the HI scale on measuring the fatigue level and functional abilities of patients, which requires further investigation.</p>
<p>Our study has some limitations. Firstly, our study focused exclusively on AS patients who met the modified New York criteria, which may limit the applicability of the findings to non-radiographic axSpA cases. Secondly, as this is a cross-sectional study, any conclusions drawn regarding causality should be considered provisional. Additionally, MRI of the sacroiliac joints and spine may serve as a potential marker for disease activity (<xref ref-type="bibr" rid="ref52">52</xref>). However, this study did not include MRI evaluation criteria to define disease activity, which may have resulted in the inability to perform a more comprehensive assessment of the patients&#x2019; disease activity.</p>
<p>In summary, the quality of life of AS patients is related to their daily functional abilities and activities; moreover, disease activity also affects patients&#x2019; quality of life. Our findings may drive attention to pharmacotherapy and exercise rehabilitation exercises to reduce disease activity and enhance mobility and functionality in patients with AS. Additionally, healthcare professionals should tailor treatment plans to the individual circumstances of patients to improve compliance, while family members should provide sufficient support and care to enhance the overall quality of life for patients.</p>
</sec>
</sec>
</body>
<back>
<sec sec-type="data-availability" id="sec25">
<title>Data availability statement</title>
<p>The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding authors.</p>
</sec>
<sec sec-type="ethics-statement" id="sec26">
<title>Ethics statement</title>
<p>The studies involving humans were approved by the First Affiliated Hospital of Shantou University Medical College. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.</p>
</sec>
<sec sec-type="author-contributions" id="sec27">
<title>Author contributions</title>
<p>AL: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing &#x2013; original draft, Writing &#x2013; review &#x0026; editing. RL: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing &#x2013; original draft, Writing &#x2013; review &#x0026; editing. LW: Conceptualization, Investigation, Methodology, Writing &#x2013; original draft. MC: Funding acquisition, Investigation, Validation, Writing &#x2013; original draft. JC: Conceptualization, Investigation, Methodology, Validation, Writing &#x2013; original draft. YG: Project administration, Supervision, Writing &#x2013; review &#x0026; editing. SZ: Project administration, Supervision, Writing &#x2013; review &#x0026; editing.</p>
</sec>
<sec sec-type="funding-information" id="sec28">
<title>Funding</title>
<p>The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This research was supported by Undergraduate Innovation and Entrepreneurship Training Program (201810560253).</p>
</sec>
<ack>
<p>We specially thank the participants who made this study possible.</p>
</ack>
<sec sec-type="COI-statement" id="sec29">
<title>Conflict of interest</title>
<p>The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
<sec sec-type="disclaimer" id="sec30">
<title>Publisher&#x2019;s note</title>
<p>All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.</p>
</sec>
<ref-list>
<title>References</title>
<ref id="ref1"><label>1.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Graham</surname> <given-names>P</given-names></name></person-group>. <article-title>Ankylosing Spondylitis</article-title>. <source>Orthop Nurs</source>. (<year>2023</year>) <volume>42</volume>:<fpage>128</fpage>&#x2013;<lpage>31</lpage>. doi: <pub-id pub-id-type="doi">10.1097/NOR.0000000000000938</pub-id></citation></ref>
<ref id="ref2"><label>2.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Zeng</surname> <given-names>S</given-names></name> <name><surname>Gong</surname> <given-names>Y</given-names></name> <name><surname>Zhang</surname> <given-names>Y</given-names></name> <name><surname>Chen</surname> <given-names>S</given-names></name> <name><surname>Chen</surname> <given-names>J</given-names></name> <name><surname>Lin</surname> <given-names>C</given-names></name> <etal/></person-group>. <article-title>Changes in the prevalence of rheumatic diseases in Shantou, China, in the Past Three Decades: A COPCORD Study</article-title>. <source>PLoS One</source>. (<year>2015</year>) <volume>10</volume>:<fpage>e0138492</fpage>. doi: <pub-id pub-id-type="doi">10.1371/journal.pone.0138492</pub-id></citation></ref>
<ref id="ref3"><label>3.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Mauro</surname> <given-names>D</given-names></name> <name><surname>Thomas</surname> <given-names>R</given-names></name> <name><surname>Guggino</surname> <given-names>G</given-names></name> <name><surname>Lories</surname> <given-names>R</given-names></name> <name><surname>Brown</surname> <given-names>MA</given-names></name> <name><surname>Ciccia</surname> <given-names>F</given-names></name></person-group>. <article-title>Ankylosing spondylitis: an autoimmune or autoinflammatory disease?</article-title> <source>Nat Rev Rheumatol</source>. (<year>2021</year>) <volume>17</volume>:<fpage>387</fpage>&#x2013;<lpage>404</lpage>. doi: <pub-id pub-id-type="doi">10.1038/s41584-021-00625-y</pub-id></citation></ref>
<ref id="ref4"><label>4.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Kiltz</surname> <given-names>U</given-names></name> <name><surname>van der Heijde</surname> <given-names>D</given-names></name></person-group>. <article-title>Health-related quality of life in patients with rheumatoid arthritis and in patients with ankylosing spondylitis</article-title>. <source>Clin Exp Rheumatol</source>. (<year>2009</year>) <volume>27</volume>:<fpage>S108</fpage>&#x2013;<lpage>11</lpage>.</citation></ref>
<ref id="ref5"><label>5.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Zhang</surname> <given-names>X</given-names></name> <name><surname>Yang</surname> <given-names>Q</given-names></name> <name><surname>Huang</surname> <given-names>J</given-names></name> <name><surname>Lin</surname> <given-names>H</given-names></name> <name><surname>Luo</surname> <given-names>N</given-names></name> <name><surname>Tang</surname> <given-names>H</given-names></name></person-group>. <article-title>Association of the newly proposed dietary index for gut microbiota and depression: the mediation effect of phenotypic age and body mass index</article-title>. <source>Eur Arch Psychiatry Clin Neurosci</source>. (<year>2024</year>). doi: <pub-id pub-id-type="doi">10.1007/s00406-024-01912-x</pub-id></citation></ref>
<ref id="ref6"><label>6.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Lee</surname> <given-names>S</given-names></name> <name><surname>Lee</surname> <given-names>JY</given-names></name> <name><surname>Hwang</surname> <given-names>JH</given-names></name> <name><surname>Shin</surname> <given-names>JH</given-names></name> <name><surname>Kim</surname> <given-names>T-H</given-names></name> <name><surname>Kim</surname> <given-names>S-K</given-names></name></person-group>. <article-title>Clinical importance of inflammatory facet joints of the spine in ankylosing spondylitis: a magnetic resonance imaging study</article-title>. <source>Scand J Rheumatol</source>. (<year>2016</year>) <volume>45</volume>:<fpage>491</fpage>&#x2013;<lpage>8</lpage>. doi: <pub-id pub-id-type="doi">10.3109/03009742.2016.1150506</pub-id></citation></ref>
<ref id="ref7"><label>7.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Magrey</surname> <given-names>M</given-names></name> <name><surname>Wei</surname> <given-names>JC-C</given-names></name> <name><surname>Yndestad</surname> <given-names>A</given-names></name> <name><surname>Bushmakin</surname> <given-names>AG</given-names></name> <name><surname>Cappelleri</surname> <given-names>JC</given-names></name> <name><surname>Dina</surname> <given-names>O</given-names></name> <etal/></person-group>. <article-title>Relationships of work productivity and activity impairment with patient-reported outcomes in ankylosing spondylitis: results from two trials</article-title>. <source>Arthritis Care Res</source>. (<year>2024</year>) <volume>76</volume>:<fpage>359</fpage>&#x2013;<lpage>65</lpage>. doi: <pub-id pub-id-type="doi">10.1002/acr.25267</pub-id></citation></ref>
<ref id="ref8"><label>8.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Kiltz</surname> <given-names>U</given-names></name> <name><surname>van der Heijde</surname> <given-names>D</given-names></name> <name><surname>Boonen</surname> <given-names>A</given-names></name> <name><surname>Braun</surname> <given-names>J</given-names></name></person-group>. <article-title>The ASAS health index (ASAS HI) - a new tool to assess the health status of patients with spondyloarthritis</article-title>. <source>Clin Exp Rheumatol</source>. (<year>2014</year>) <volume>32</volume>:<fpage>S-105-108</fpage>.</citation></ref>
<ref id="ref9"><label>9.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Kiltz</surname> <given-names>U</given-names></name> <name><surname>van der Heijde</surname> <given-names>D</given-names></name> <name><surname>Boonen</surname> <given-names>A</given-names></name> <name><surname>Cieza</surname> <given-names>A</given-names></name> <name><surname>Stucki</surname> <given-names>G</given-names></name> <name><surname>Khan</surname> <given-names>MA</given-names></name> <etal/></person-group>. <article-title>Development of a health index in patients with ankylosing spondylitis (ASAS HI): final result of a global initiative based on the ICF guided by ASAS</article-title>. <source>Ann Rheum Dis</source>. (<year>2015</year>) <volume>74</volume>:<fpage>830</fpage>&#x2013;<lpage>5</lpage>. doi: <pub-id pub-id-type="doi">10.1136/annrheumdis-2013-203967</pub-id></citation></ref>
<ref id="ref10"><label>10.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Rudwaleit</surname> <given-names>M</given-names></name> <name><surname>van der Heijde</surname> <given-names>D</given-names></name> <name><surname>Landew&#x00E9;</surname> <given-names>R</given-names></name> <name><surname>Akkoc</surname> <given-names>N</given-names></name> <name><surname>Brandt</surname> <given-names>J</given-names></name> <name><surname>Chou</surname> <given-names>CT</given-names></name> <etal/></person-group>. <article-title>The assessment of SpondyloArthritis international society classification criteria for peripheral spondyloarthritis and for spondyloarthritis in general</article-title>. <source>Ann Rheum Dis</source>. (<year>2011</year>) <volume>70</volume>:<fpage>25</fpage>&#x2013;<lpage>31</lpage>. doi: <pub-id pub-id-type="doi">10.1136/ard.2010.133645</pub-id></citation></ref>
<ref id="ref11"><label>11.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Alonso-Castro</surname> <given-names>S</given-names></name> <name><surname>Pardo</surname> <given-names>E</given-names></name> <name><surname>Charca</surname> <given-names>L</given-names></name> <name><surname>Pino</surname> <given-names>M</given-names></name> <name><surname>Fern&#x00E1;ndez</surname> <given-names>S</given-names></name> <name><surname>Alperi</surname> <given-names>M</given-names></name> <etal/></person-group>. <article-title>Performance of the ASAS health index for the evaluation of Spondyloarthritis in daily practice</article-title>. <source>J Rheumatol</source>. (<year>2020</year>) <volume>47</volume>:<fpage>1483</fpage>&#x2013;<lpage>9</lpage>. doi: <pub-id pub-id-type="doi">10.3899/jrheum.200025</pub-id></citation></ref>
<ref id="ref12"><label>12.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>van der Linden</surname> <given-names>S</given-names></name> <name><surname>Valkenburg</surname> <given-names>HA</given-names></name> <name><surname>Cats</surname> <given-names>A</given-names></name></person-group>. <article-title>Evaluation of diagnostic criteria for ankylosing spondylitis. A proposal for modification of the New York criteria</article-title>. <source>Arthritis Rheum</source>. (<year>1984</year>) <volume>27</volume>:<fpage>361</fpage>&#x2013;<lpage>8</lpage>. doi: <pub-id pub-id-type="doi">10.1002/art.1780270401</pub-id></citation></ref>
<ref id="ref13"><label>13.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Alonso</surname> <given-names>S</given-names></name> <name><surname>Morante</surname> <given-names>I</given-names></name> <name><surname>Alperi</surname> <given-names>M</given-names></name> <name><surname>Queiro</surname> <given-names>R</given-names></name></person-group>. <article-title>The ASAS health index: a new era for health impact assessment in Spondyloarthritis</article-title>. <source>J Rheumatol</source>. (<year>2022</year>) <volume>49</volume>:<fpage>8</fpage>&#x2013;<lpage>15</lpage>. doi: <pub-id pub-id-type="doi">10.3899/jrheum.200586</pub-id></citation></ref>
<ref id="ref14"><label>14.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Jones</surname> <given-names>SD</given-names></name> <name><surname>Steiner</surname> <given-names>A</given-names></name> <name><surname>Garrett</surname> <given-names>SL</given-names></name> <name><surname>Calin</surname> <given-names>A</given-names></name></person-group>. <article-title>The Bath ankylosing spondylitis patient global score (BAS-G)</article-title>. <source>Br J Rheumatol</source>. (<year>1996</year>) <volume>35</volume>:<fpage>66</fpage>&#x2013;<lpage>71</lpage>. doi: <pub-id pub-id-type="doi">10.1093/rheumatology/35.1.66</pub-id></citation></ref>
<ref id="ref15"><label>15.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Abdal</surname> <given-names>SJ</given-names></name> <name><surname>Yesmin</surname> <given-names>S</given-names></name> <name><surname>Shazzad</surname> <given-names>MN</given-names></name> <name><surname>Azad</surname> <given-names>MAK</given-names></name> <name><surname>Shahin</surname> <given-names>MA</given-names></name> <name><surname>Choudhury</surname> <given-names>MR</given-names></name> <etal/></person-group>. <article-title>Development of a Bangla version of the Bath ankylosing spondylitis disease activity index (BASDAI) and the Bath ankylosing spondylitis functional index (BASFI)</article-title>. <source>Int J Rheum Dis</source>. (<year>2021</year>) <volume>24</volume>:<fpage>74</fpage>&#x2013;<lpage>80</lpage>. doi: <pub-id pub-id-type="doi">10.1111/1756-185X.14008</pub-id></citation></ref>
<ref id="ref16"><label>16.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Kwan</surname> <given-names>YH</given-names></name> <name><surname>Tan</surname> <given-names>JJ</given-names></name> <name><surname>Phang</surname> <given-names>JK</given-names></name> <name><surname>Fong</surname> <given-names>W</given-names></name> <name><surname>Lim</surname> <given-names>KK</given-names></name> <name><surname>Koh</surname> <given-names>HL</given-names></name> <etal/></person-group>. <article-title>Validity and reliability of the ankylosing spondylitis disease activity score with C-reactive protein (ASDAS-CRP) and Bath ankylosing spondylitis disease activity index (BASDAI) in patients with axial spondyloarthritis (axSpA) in Singapore</article-title>. <source>Int J Rheum Dis</source>. (<year>2019</year>) <volume>22</volume>:<fpage>2206</fpage>&#x2013;<lpage>12</lpage>. doi: <pub-id pub-id-type="doi">10.1111/1756-185X.13735</pub-id></citation></ref>
<ref id="ref17"><label>17.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Schneeberger</surname> <given-names>EE</given-names></name> <name><surname>Zamora</surname> <given-names>N</given-names></name> <name><surname>Citera</surname> <given-names>G</given-names></name></person-group>. <article-title>SASDAS (simplified version of ankylosing spondylitis disease activity score)-ESR performance and development of SASDAS-CRP and their agreement with ASDAS-ESR and ASDAS-CRP in patients with ankylosing spondylitis</article-title>. <source>Clin Rheumatol</source>. (<year>2016</year>) <volume>35</volume>:<fpage>2865</fpage>&#x2013;<lpage>6</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s10067-016-3342-6</pub-id></citation></ref>
<ref id="ref18"><label>18.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Jonsson</surname> <given-names>K</given-names></name> <name><surname>Peterson</surname> <given-names>M</given-names></name></person-group>. <article-title>Peak expiratory flow rate and thoracic mobility in people with fibromyalgia. A cross sectional study</article-title>. <source>Scand J Pain</source>. (<year>2019</year>) <volume>19</volume>:<fpage>755</fpage>&#x2013;<lpage>63</lpage>. doi: <pub-id pub-id-type="doi">10.1515/sjpain-2019-0044</pub-id></citation></ref>
<ref id="ref19"><label>19.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Tousignant</surname> <given-names>M</given-names></name> <name><surname>Poulin</surname> <given-names>L</given-names></name> <name><surname>Marchand</surname> <given-names>S</given-names></name> <name><surname>Viau</surname> <given-names>A</given-names></name> <name><surname>Place</surname> <given-names>C</given-names></name></person-group>. <article-title>The modified-modified Schober test for range of motion assessment of lumbar flexion in patients with low back pain: a study of criterion validity, intra- and inter-rater reliability and minimum metrically detectable change</article-title>. <source>Disabil Rehabil</source>. (<year>2005</year>) <volume>27</volume>:<fpage>553</fpage>&#x2013;<lpage>9</lpage>. doi: <pub-id pub-id-type="doi">10.1080/09638280400018411</pub-id></citation></ref>
<ref id="ref20"><label>20.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Guo</surname> <given-names>G</given-names></name> <name><surname>Zhang</surname> <given-names>Y</given-names></name> <name><surname>Lin</surname> <given-names>D</given-names></name> <name><surname>Chen</surname> <given-names>Z</given-names></name> <name><surname>Yan</surname> <given-names>Q</given-names></name> <name><surname>Gao</surname> <given-names>F</given-names></name> <etal/></person-group>. <article-title>Correlation of finger-to-floor distance with the spinal mobility, spinal function indices and initial determination of its optimal cutoff value: a multicentre case-control study</article-title>. <source>Front Med</source>. (<year>2023</year>) <volume>10</volume>:<fpage>1135748</fpage>. doi: <pub-id pub-id-type="doi">10.3389/fmed.2023.1135748</pub-id></citation></ref>
<ref id="ref21"><label>21.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Hawrylak</surname> <given-names>A</given-names></name> <name><surname>Chromik</surname> <given-names>K</given-names></name> <name><surname>Ratajczak</surname> <given-names>B</given-names></name> <name><surname>Barczyk-Pawelec</surname> <given-names>K</given-names></name> <name><surname>Demczuk-W&#x0142;odarczyk</surname> <given-names>E</given-names></name></person-group>. <article-title>Spinal range of motion and plantar pressure in sport climbers</article-title>. <source>Acta Bioeng Biomech</source>. (<year>2017</year>) <volume>19</volume>:<fpage>169</fpage>&#x2013;<lpage>73</lpage>. PMID: <pub-id pub-id-type="pmid">28869622</pub-id></citation></ref>
<ref id="ref22"><label>22.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Aino</surname> <given-names>M</given-names></name> <name><surname>Oka</surname> <given-names>S</given-names></name> <name><surname>Haruguchi</surname> <given-names>K</given-names></name> <name><surname>Aino</surname> <given-names>M</given-names></name> <name><surname>Hashimura</surname> <given-names>S</given-names></name> <name><surname>Kurosawa</surname> <given-names>K</given-names></name></person-group>. <article-title>Comparison of spinal column alignment and autonomic nervous activity using the intersegmental tenderness test in the segment above</article-title>. <source>J Phys Ther Sci</source>. (<year>2021</year>) <volume>33</volume>:<fpage>570</fpage>&#x2013;<lpage>5</lpage>. doi: <pub-id pub-id-type="doi">10.1589/jpts.33.570</pub-id></citation></ref>
<ref id="ref23"><label>23.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Liu</surname> <given-names>P</given-names></name> <name><surname>Zhou</surname> <given-names>J</given-names></name> <name><surname>Cui</surname> <given-names>H</given-names></name> <name><surname>Xu</surname> <given-names>J</given-names></name> <name><surname>Ruan</surname> <given-names>G</given-names></name> <name><surname>Ding</surname> <given-names>C</given-names></name> <etal/></person-group>. <article-title>Vitamin D plays a protective role in osteoarthritis by regulating AMPK/mTOR signalling pathway to activate chondrocyte autophagy</article-title>. <source>Clin Exp Rheumatol</source>. (<year>2023</year>) <volume>42</volume>:<fpage>736</fpage>&#x2013;<lpage>45</lpage>. doi: <pub-id pub-id-type="doi">10.55563/clinexprheumatol/chmuts</pub-id></citation></ref>
<ref id="ref24"><label>24.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Baraliakos</surname> <given-names>X</given-names></name> <name><surname>Braun</surname> <given-names>J</given-names></name></person-group>. <article-title>Imaging scoring methods in axial Spondyloarthritis</article-title>. <source>Rheum Dis Clin N Am</source>. (<year>2016</year>) <volume>42</volume>:<fpage>663</fpage>&#x2013;<lpage>78</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.rdc.2016.07.006</pub-id></citation></ref>
<ref id="ref25"><label>25.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Raychaudhuri</surname> <given-names>SP</given-names></name> <name><surname>Deodhar</surname> <given-names>A</given-names></name></person-group>. <article-title>The classification and diagnostic criteria of ankylosing spondylitis</article-title>. <source>J Autoimmun</source>. (<year>2014</year>) <volume>48&#x2013;49</volume>:<fpage>128</fpage>&#x2013;<lpage>33</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.jaut.2014.01.015</pub-id></citation></ref>
<ref id="ref26"><label>26.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Xu</surname> <given-names>T</given-names></name> <name><surname>Huang</surname> <given-names>Z</given-names></name> <name><surname>Li</surname> <given-names>B</given-names></name> <name><surname>Jin</surname> <given-names>H</given-names></name> <name><surname>Zhang</surname> <given-names>J</given-names></name> <name><surname>Yang</surname> <given-names>H</given-names></name> <etal/></person-group>. <article-title>Association between home and community-based services utilization and self-rated health among Chinese older adults with chronic diseases: evidence from the 2018 China health and retirement longitudinal study</article-title>. <source>BMC Public Health</source>. (<year>2024</year>) <volume>24</volume>:<fpage>117</fpage>. doi: <pub-id pub-id-type="doi">10.1186/s12889-023-17535-1</pub-id></citation></ref>
<ref id="ref27"><label>27.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Ibrahimagi&#x0107;</surname> <given-names>O&#x0106;</given-names></name> <name><surname>Tadi&#x0107;</surname> <given-names>A</given-names></name> <name><surname>Kuni&#x0107;</surname> <given-names>S</given-names></name> <name><surname>Smajlovi&#x0107;</surname> <given-names>D</given-names></name> <name><surname>Dostovi&#x0107;</surname> <given-names>Z</given-names></name> <name><surname>Iljazovi&#x0107;</surname> <given-names>A</given-names></name></person-group>. <article-title>Oleh Hornykiewicz (1926-2020): sixty years since the pioneering L-DOPA application - one year since the death of the Pioneer</article-title>. <source>Psychiatr Danub</source>. (<year>2021</year>) <volume>33</volume>:<fpage>1204</fpage>&#x2013;<lpage>9</lpage>.</citation></ref>
<ref id="ref28"><label>28.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Choi</surname> <given-names>M</given-names></name> <name><surname>Goh</surname> <given-names>TS</given-names></name> <name><surname>Kim</surname> <given-names>DS</given-names></name> <name><surname>Son</surname> <given-names>SM</given-names></name> <name><surname>Lee</surname> <given-names>JS</given-names></name></person-group>. <article-title>Validation of the Korean ankylosing spondylitis quality of life questionnaire, Clin</article-title>. <source>Orthop Surg</source>. (<year>2023</year>) <volume>15</volume>:<fpage>968</fpage>&#x2013;<lpage>74</lpage>. doi: <pub-id pub-id-type="doi">10.4055/cios23143</pub-id></citation></ref>
<ref id="ref29"><label>29.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Webster</surname> <given-names>K</given-names></name> <name><surname>Cella</surname> <given-names>D</given-names></name> <name><surname>Yost</surname> <given-names>K</given-names></name></person-group>. <article-title>The functional assessment of chronic illness therapy (FACIT) measurement system: properties, applications, and interpretation</article-title>. <source>Health Qual Life Outcomes</source>. (<year>2003</year>) <volume>1</volume>:<fpage>79</fpage>. doi: <pub-id pub-id-type="doi">10.1186/1477-7525-1-79</pub-id></citation></ref>
<ref id="ref30"><label>30.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>van Weely</surname> <given-names>SFE</given-names></name> <name><surname>van Denderen</surname> <given-names>CJ</given-names></name> <name><surname>van der Horst-Bruinsma</surname> <given-names>IE</given-names></name> <name><surname>Nurmohamed</surname> <given-names>MT</given-names></name> <name><surname>Dijkmans</surname> <given-names>BAC</given-names></name> <name><surname>Dekker</surname> <given-names>J</given-names></name> <etal/></person-group>. <article-title>Reproducibility of performance measures of physical function based on the BASFI, in ankylosing spondylitis</article-title>. <source>Rheumatology</source>. (<year>2009</year>) <volume>48</volume>:<fpage>1254</fpage>&#x2013;<lpage>60</lpage>. doi: <pub-id pub-id-type="doi">10.1093/rheumatology/kep190</pub-id></citation></ref>
<ref id="ref31"><label>31.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Franchignoni</surname> <given-names>F</given-names></name> <name><surname>Salaffi</surname> <given-names>F</given-names></name> <name><surname>Ciapetti</surname> <given-names>A</given-names></name> <name><surname>Giordano</surname> <given-names>A</given-names></name></person-group>. <article-title>Searching for optimal rating scales in the Bath ankylosing spondylitis functional index (BASFI) and Bath ankylosing spondylitis disease activity index (BASDAI)</article-title>. <source>Rheumatol Int</source>. (<year>2014</year>) <volume>34</volume>:<fpage>171</fpage>&#x2013;<lpage>3</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s00296-013-2891-0</pub-id></citation></ref>
<ref id="ref32"><label>32.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Redeker</surname> <given-names>I</given-names></name> <name><surname>Landew&#x00E9;</surname> <given-names>R</given-names></name> <name><surname>van der Heijde</surname> <given-names>D</given-names></name> <name><surname>Ramiro</surname> <given-names>S</given-names></name> <name><surname>Boonen</surname> <given-names>A</given-names></name> <name><surname>Dougados</surname> <given-names>M</given-names></name> <etal/></person-group>. <article-title>Impact of disease outcomes on the assessment of SpondyloArthritis international society health index (ASAS HI): a Bayesian network analysis of the DESIR cohort</article-title>. <source>RMD Open</source>. (<year>2023</year>) <volume>9</volume>:<fpage>e003587</fpage>. doi: <pub-id pub-id-type="doi">10.1136/rmdopen-2023-003587</pub-id></citation></ref>
<ref id="ref33"><label>33.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Zochling</surname> <given-names>J</given-names></name></person-group>. <article-title>Measures of symptoms and disease status in ankylosing spondylitis: ankylosing spondylitis disease activity score (ASDAS), ankylosing spondylitis quality of life scale (ASQoL), Bath ankylosing spondylitis disease activity index (BASDAI), Bath ankylosing spondylitis functional index (BASFI), Bath ankylosing spondylitis global score (BAS-G), Bath ankylosing spondylitis metrology index (BASMI), Dougados functional index (DFI), and health assessment questionnaire for the Spondylarthropathies (HAQ-S)</article-title>. <source>Arthritis Care Res</source>. (<year>2011</year>) <volume>63</volume>:<fpage>S47</fpage>&#x2013;<lpage>58</lpage>. doi: <pub-id pub-id-type="doi">10.1002/acr.20575</pub-id></citation></ref>
<ref id="ref34"><label>34.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Chung</surname> <given-names>DXY</given-names></name> <name><surname>Loo</surname> <given-names>YE</given-names></name> <name><surname>Kwan</surname> <given-names>YH</given-names></name> <name><surname>Phang</surname> <given-names>JK</given-names></name> <name><surname>Woon</surname> <given-names>TH</given-names></name> <name><surname>Goh</surname> <given-names>WR</given-names></name> <etal/></person-group>. <article-title>Association of anxiety, depression and resilience with overall health and functioning in axial spondyloarthritis (axSpA): a cross-sectional study</article-title>. <source>BMJ Open</source>. (<year>2023</year>) <volume>13</volume>:<fpage>e071944</fpage>. doi: <pub-id pub-id-type="doi">10.1136/bmjopen-2023-071944</pub-id></citation></ref>
<ref id="ref35"><label>35.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Qu</surname> <given-names>X</given-names></name> <name><surname>Xu</surname> <given-names>X</given-names></name> <name><surname>Jiang</surname> <given-names>Q</given-names></name> <name><surname>Chen</surname> <given-names>Y</given-names></name> <name><surname>Geng</surname> <given-names>Z</given-names></name> <name><surname>Yang</surname> <given-names>K</given-names></name> <etal/></person-group>. <article-title>Clinical performance of the ASAS health index in chinese patients with ankylosing spondylitis and its influencing factors</article-title>. <source>Clin Rheumatol</source>. (<year>2024</year>) <volume>43</volume>:<fpage>2541</fpage>&#x2013;<lpage>50</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s10067-024-07045-9</pub-id></citation></ref>
<ref id="ref36"><label>36.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>P&#x00E9;courneau</surname> <given-names>V</given-names></name> <name><surname>Degbo&#x00E9;</surname> <given-names>Y</given-names></name> <name><surname>Barnetche</surname> <given-names>T</given-names></name> <name><surname>Cantagrel</surname> <given-names>A</given-names></name> <name><surname>Constantin</surname> <given-names>A</given-names></name> <name><surname>Ruyssen-Witrand</surname> <given-names>A</given-names></name></person-group>. <article-title>Effectiveness of exercise programs in ankylosing spondylitis: a Meta-analysis of randomized controlled trials</article-title>. <source>Arch Phys Med Rehabil</source>. (<year>2018</year>) <volume>99</volume>:<fpage>383</fpage>&#x2013;<lpage>389.e1</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.apmr.2017.07.015</pub-id></citation></ref>
<ref id="ref37"><label>37.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Hosseini</surname> <given-names>M</given-names></name> <name><surname>Rahimibarghani</surname> <given-names>S</given-names></name> <name><surname>Ghorbanpour</surname> <given-names>S</given-names></name> <name><surname>Movassaghi</surname> <given-names>S</given-names></name> <name><surname>Emami-Razavi</surname> <given-names>SZ</given-names></name> <name><surname>Azadvari</surname> <given-names>M</given-names></name> <etal/></person-group>. <article-title>The effects of supervision on the outcomes of exercise training in patients with ankylosing spondylitis: a single-blind randomized controlled trial</article-title>. <source>Int J Rheum Dis</source>. (<year>2023</year>) <volume>26</volume>:<fpage>1120</fpage>&#x2013;<lpage>8</lpage>. doi: <pub-id pub-id-type="doi">10.1111/1756-185X.14711</pub-id></citation></ref>
<ref id="ref38"><label>38.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Jennings</surname> <given-names>F</given-names></name> <name><surname>Oliveira</surname> <given-names>HA</given-names></name> <name><surname>de Souza</surname> <given-names>MC</given-names></name> <name><surname>da Gra&#x00E7;a Cruz</surname> <given-names>V</given-names></name> <name><surname>Natour</surname> <given-names>J</given-names></name></person-group>. <article-title>Effects of aerobic training in patients with ankylosing spondylitis</article-title>. <source>J Rheumatol</source>. (<year>2015</year>) <volume>42</volume>:<fpage>2347</fpage>&#x2013;<lpage>53</lpage>. doi: <pub-id pub-id-type="doi">10.3899/jrheum.150518</pub-id></citation></ref>
<ref id="ref39"><label>39.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Chung</surname> <given-names>HY</given-names></name> <name><surname>Lau</surname> <given-names>CS</given-names></name> <name><surname>Wu</surname> <given-names>KP</given-names></name> <name><surname>Wong</surname> <given-names>WS</given-names></name> <name><surname>Mok</surname> <given-names>MY</given-names></name></person-group>. <article-title>Comparison of performance of the assessment of SpondyloArthritis international society, the European Spondyloarthropathy study group and the modified New York criteria in a cohort of Chinese patients with spondyloarthritis</article-title>. <source>Clin Rheumatol</source>. (<year>2011</year>) <volume>30</volume>:<fpage>947</fpage>&#x2013;<lpage>53</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s10067-011-1693-6</pub-id></citation></ref>
<ref id="ref40"><label>40.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Madsen</surname> <given-names>OR</given-names></name></person-group>. <article-title>Stability of fatigue, pain, patient global assessment and the Bath ankylosing spondylitis functional index (BASFI) in spondyloarthropathy patients with stable disease according to the Bath ankylosing spondylitis disease activity index (BASDAI)</article-title>. <source>Rheumatol Int</source>. (<year>2018</year>) <volume>38</volume>:<fpage>425</fpage>&#x2013;<lpage>32</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s00296-017-3920-1</pub-id></citation></ref>
<ref id="ref41"><label>41.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Wang</surname> <given-names>M</given-names></name> <name><surname>Wang</surname> <given-names>S</given-names></name> <name><surname>Zhang</surname> <given-names>X</given-names></name> <name><surname>Xia</surname> <given-names>Q</given-names></name> <name><surname>Cai</surname> <given-names>G</given-names></name> <name><surname>Yang</surname> <given-names>X</given-names></name> <etal/></person-group>. <article-title>Analysis on the situation of subjective well-being and its influencing factors in patients with ankylosing spondylitis</article-title>. <source>Health Qual Life Outcomes</source>. (<year>2016</year>) <volume>14</volume>:<fpage>118</fpage>. doi: <pub-id pub-id-type="doi">10.1186/s12955-016-0522-7</pub-id></citation></ref>
<ref id="ref42"><label>42.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Ramiro</surname> <given-names>S</given-names></name> <name><surname>Nikiphorou</surname> <given-names>E</given-names></name> <name><surname>Sepriano</surname> <given-names>A</given-names></name> <name><surname>Ortolan</surname> <given-names>A</given-names></name> <name><surname>Webers</surname> <given-names>C</given-names></name> <name><surname>Baraliakos</surname> <given-names>X</given-names></name> <etal/></person-group>. <article-title>ASAS-EULAR recommendations for the management of axial spondyloarthritis</article-title>. <source>Ann Rheum Dis</source>. (<year>2022</year>) <volume>82</volume>:<fpage>19</fpage>&#x2013;<lpage>34</lpage>. doi: <pub-id pub-id-type="doi">10.1136/ard-2022-223296</pub-id></citation></ref>
<ref id="ref43"><label>43.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Kedyk</surname> <given-names>I</given-names></name> <name><surname>Stanislavchuk</surname> <given-names>M</given-names></name></person-group>. <article-title>Clinical characteristics of ankylosing spondylitis patients depending on neuropathic pain</article-title>. <source>Reumatologia</source>. (<year>2023</year>) <volume>61</volume>:<fpage>104</fpage>&#x2013;<lpage>8</lpage>. doi: <pub-id pub-id-type="doi">10.5114/reum/163223</pub-id></citation></ref>
<ref id="ref44"><label>44.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Bond</surname> <given-names>D</given-names></name></person-group>. <article-title>Ankylosing spondylitis: diagnosis and management</article-title>. <source>Nurs Stand</source>. (<year>2013</year>) <volume>28</volume>:<fpage>52</fpage>&#x2013;<lpage>9</lpage>. doi: <pub-id pub-id-type="doi">10.7748/ns2013.12.28.16.52.e7807</pub-id></citation></ref>
<ref id="ref45"><label>45.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Braun</surname> <given-names>J</given-names></name> <name><surname>Sieper</surname> <given-names>J</given-names></name></person-group>. <article-title>Ankylosing spondylitis</article-title>. <source>Lancet</source>. (<year>2007</year>) <volume>369</volume>:<fpage>1379</fpage>&#x2013;<lpage>90</lpage>. doi: <pub-id pub-id-type="doi">10.1016/S0140-6736(07)60635-7</pub-id></citation></ref>
<ref id="ref46"><label>46.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Xiong</surname> <given-names>Y</given-names></name> <name><surname>Cai</surname> <given-names>M</given-names></name> <name><surname>Xu</surname> <given-names>Y</given-names></name> <name><surname>Dong</surname> <given-names>P</given-names></name> <name><surname>Chen</surname> <given-names>H</given-names></name> <name><surname>He</surname> <given-names>W</given-names></name> <etal/></person-group>. <article-title>Joint together: the etiology and pathogenesis of ankylosing spondylitis</article-title>. <source>Front Immunol</source>. (<year>2022</year>) <volume>13</volume>:<fpage>996103</fpage>. doi: <pub-id pub-id-type="doi">10.3389/fimmu.2022.996103</pub-id></citation></ref>
<ref id="ref47"><label>47.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Sieper</surname> <given-names>J</given-names></name> <name><surname>Poddubnyy</surname> <given-names>D</given-names></name></person-group>. <article-title>Axial spondyloarthritis</article-title>. <source>Lancet</source>. (<year>2017</year>) <volume>390</volume>:<fpage>73</fpage>&#x2013;<lpage>84</lpage>. doi: <pub-id pub-id-type="doi">10.1016/S0140-6736(16)31591-4</pub-id></citation></ref>
<ref id="ref48"><label>48.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Kwan</surname> <given-names>YH</given-names></name> <name><surname>Fong</surname> <given-names>W</given-names></name> <name><surname>Cheng</surname> <given-names>GHL</given-names></name> <name><surname>Phang</surname> <given-names>JK</given-names></name> <name><surname>Leung</surname> <given-names>YY</given-names></name> <name><surname>Lui</surname> <given-names>NL</given-names></name> <etal/></person-group>. <article-title>The mediating role of pain and function in the association between stiffness and quality of life in patients with axial spondyloarthritis</article-title>. <source>Semin Arthritis Rheum</source>. (<year>2019</year>) <volume>49</volume>:<fpage>377</fpage>&#x2013;<lpage>80</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.semarthrit.2019.02.010</pub-id></citation></ref>
<ref id="ref49"><label>49.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Kiefer</surname> <given-names>D</given-names></name> <name><surname>Braun</surname> <given-names>J</given-names></name> <name><surname>Chatzistefanidi</surname> <given-names>V</given-names></name> <name><surname>Kiltz</surname> <given-names>U</given-names></name> <name><surname>Adolf</surname> <given-names>D</given-names></name> <name><surname>Schwarze</surname> <given-names>I</given-names></name> <etal/></person-group>. <article-title>Clinical relevance of axial radiographic damage in axial Spondyloarthritis: evaluation of functional consequences by an objective electronic device</article-title>. <source>J Rheumatol</source>. (<year>2023</year>) <volume>50</volume>:<fpage>1422</fpage>&#x2013;<lpage>9</lpage>. doi: <pub-id pub-id-type="doi">10.3899/jrheum.2022-1240</pub-id></citation></ref>
<ref id="ref50"><label>50.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Protopopov</surname> <given-names>M</given-names></name> <name><surname>Sieper</surname> <given-names>J</given-names></name> <name><surname>Haibel</surname> <given-names>H</given-names></name> <name><surname>Listing</surname> <given-names>J</given-names></name> <name><surname>Rudwaleit</surname> <given-names>M</given-names></name> <name><surname>Poddubnyy</surname> <given-names>D</given-names></name></person-group>. <article-title>Relevance of structural damage in the sacroiliac joints for the functional status and spinal mobility in patients with axial spondyloarthritis: results from the German Spondyloarthritis inception cohort</article-title>. <source>Arthritis Res Ther</source>. (<year>2017</year>) <volume>19</volume>:<fpage>240</fpage>. doi: <pub-id pub-id-type="doi">10.1186/s13075-017-1453-3</pub-id></citation></ref>
<ref id="ref51"><label>51.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Kiefer</surname> <given-names>D</given-names></name> <name><surname>Braun</surname> <given-names>J</given-names></name> <name><surname>Kiltz</surname> <given-names>U</given-names></name> <name><surname>Chatzistefanidi</surname> <given-names>V</given-names></name> <name><surname>Adolf</surname> <given-names>D</given-names></name> <name><surname>Schwarze</surname> <given-names>I</given-names></name> <etal/></person-group>. <article-title>Global functioning in axial Spondyloarthritis is stronger associated with disease activity and function than with mobility and radiographic damage</article-title>. <source>Arthritis Care Res</source>. (<year>2023</year>). doi: <pub-id pub-id-type="doi">10.1002/acr.25204</pub-id></citation></ref>
<ref id="ref52"><label>52.</label><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Ostergaard</surname> <given-names>M</given-names></name> <name><surname>Poggenborg</surname> <given-names>RP</given-names></name> <name><surname>Axelsen</surname> <given-names>MB</given-names></name> <name><surname>Pedersen</surname> <given-names>SJ</given-names></name></person-group>. <article-title>Magnetic resonance imaging in spondyloarthritis--how to quantify findings and measure response</article-title>. <source>Best Pract Res Clin Rheumatol</source>. (<year>2010</year>) <volume>24</volume>:<fpage>637</fpage>&#x2013;<lpage>57</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.berh.2010.06.001</pub-id></citation></ref>
</ref-list>
</back>
</article>