Data on major osteoporotic fractures were derived from the electronic medical records (EMR) of inpatient patients of the First Affiliated Hospital of Jinzhou Medical University from a five-year period between January 1, 2018 and December 31, 2022. The First Affiliated Hospital of Jinzhou Medical University a major tertiary public hospital (one of the highest-level hospitals in China) is located in Jinzhou, the center of western Liaoning. It provides health-care services for more than 1.29 million outpatients and 0.12 million inpatients each year. This study protocol was approved by the Institute of Research Board of the First Affiliated Hospital of Jinzhou Medical University (Approval number: KYLL202392).

Inclusion criteria included the following: (1) the cause of hip, forearm and wrist or humerus fracture was with low-energy trauma (generally falls from standing height and below), and vertebral fragility fractures that occurred during the study period and (2) Patients over 50 years of age with new fractures. The exclusion criteria were: (1) fractures due to high trauma (i.e., car accident and fall from above standing height), (2) pathological fractures (i.e., bone metastasis) or secondary osteoporotic fractures (i.e., rheumatoid arthritis, chronic nutritional deficiency, hyperthyroidism, chronic obstructive pulmonary disease, Parkinson’s disease, chronic liver disease, chronic kidney disease), (3) use of glucocorticosteroid medications, (4) periprosthetic femoral fracture, (5) the fracture occurred within half a year after a previous one, and (6) it was clearly described as “old hip fracture” by physicians in diagnosis text.

This research considered major osteoporotic fractures, including hip, vertebral, forearm and wrist, and humerus; all fractures were diagnosed based on x-ray reports and extracted from the EMR. To ensure the validation of our fracture cases, we randomly called 30 fractures patients and confirmed all fracture cases. The hip fractures were classified into femoral neck, intertrochanteric femur, subtrochanteric femur and other unclassified sites (i.e., lesser trochanter, greater trochanter, femoral head). Clinical vertebral fractures were identified from T4 to L4. Forearm and wrist included radius (i.e., proximal radius, radius head), ulna (i.e., proximal ulna, ulna head), and carpal. Proximal humerus included greater tuberosity, lesser tuberosity, anatomical neck, surgical neck and humeral head. Because of the limited number of proximal humerus fractures, all proximal humerus factures were combined in the analyses without further classification. Multi-site fractures were defined as any two or more fractures of the hip, vertebrae, forearm and humerus at the same time. Prior fracture was defined as a history of any previous fracture occurred after 40 years old. Data on comminuted fractures were also collected.

We considered the following measures: patient age, year, season, hospitalization duration and the cause of fracture, comorbidities, surgical treatment of fractures, and anti-osteoporotic medications (AM) used in hospital post fracture; these data were extracted from EMR. In China, the seasons of spring, summer, autumn, and winter were from March to May, June to August, September to November, and December to February, respectively. The residence determined by checking the valid identity documents number. The causes of fracture included fall from standing height and below (the location of the fall was categorized into indoor, outdoor and unknown), sprain and other (e.g., low back pain and soreness with no apparent cause, after lifting heavy objects, bumps in the car or presented with discomfort in other parts of the body). Comorbidities assessed included type 2 diabetes mellitus (T2DM), hyperlipemia, hypertension, coronary heart disease (CHD), ischemic stroke, hemorrhagic stroke, respiratory diseases (including asthma, pneumonia, chronic bronchitis, emphysema and lung cancer), gastrointestinal diseases (including chronic gastritis, chronic enteritis, gastric cancer and colorectal cancer), which were ascertained from in-hospital diagnosis records and/or self-reported history. Hyperlipidemia was determined based on the blood lipid test results (including high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, total cholesterol and triglycerides) (12). AM included bisphosphonates (i.e., zoledronic acid, alendronate sodium, ibandronat sodium and risedronate sodium), others (i.e., alfacalcidol, salmon calcitonin and menatetrenone) and the Chinese medicine.

We descriptively analyzed the baseline characteristics, fracture sites, types, causes, comorbidities, and treatment by sex using frequencies, percentages, medians and inter-quartile ranges in males and females separately. Specially, we used the Chi-square test to compare the descriptive data including seasons, comorbidities (i.e., hyperlipemia, hypertension, ischemic stroke and respiratory diseases) between fracture sites. The Fisher exact probability method was used to compare residence between fracture sites. The Kruskal-Wallis test was used to test for differences of age, hospitalization duration, number of comorbidities between fracture sites. Test for trend of the incident fracture numbers from 2018 to 2022 by fracture site and sex was estimated from age and sex adjusted linear regression models. Two-sided P < 0.05 was considered to be statistically significant. All statistical analyses were performed using the SPSS software (version 24.0; SPSS, Chicago, IL).

We included a total of 1823 fracture patients, which involved 510 (28.0%) males and 1313 (82.0%) females ( Table 1 ). Hip, vertebral, forearm and wrist, humerus and multi-site fractures accounted for 68.4%, 22.7%, 4.1%, 2.5% and 2.2% of all fractures in males and 57.9%, 27.6%, 7.8%, 4.4% and 2.4% in females, respectively. Among those fracture patients, 108 individuals had a prior fracture (26 in men and 80 in women, respectively). Prior fracture among hip fracture patients accounted for 4.6% in males and 7.1% in females. Overall, there was an increase in fracture numbers from 2018 to 2022 in males (P for trend for any fracture =0.028; Figure 1 ); females showed a similar trend (P for trend for any fracture < 0.001). Among those with hip fractures the most common sites involved were the femoral neck (62.9%; Supplementary Table 1 ) and intertrochanteric (35.3%). For vertebral fractures, lumbar and thoracic accounted for 64.0% and 49.8%, respectively. The most common site for forearm fracture was the distal radius (92.7%). Comparable results were noted for males and females. Multi-site fracture mainly comprised hip and forearm and wrist (38.1%; Supplementary Table 2 ), vertebral and forearm (28.6%), hip and vertebral (11.9%), and hip and humerus (11.9%). Among non-vertebral comminuted fractures, forearm and wrist and humerus were the most common types in males and females ( Supplementary Table 3 ).

The overall number of fractures increased with age in males (P for trend = 0.009; Table 1 ). The majority of fractures occurred in autumn. The median length of hospitalization for any fractures was 7 days (interquartile range: 4.0-11.0 days in males and 4.0-10.0 in females). Hip fractures had the longest length of stay in males and females (median duration = 8 days in both sexes) and vertebral fractures had the shortest hospitalization duration (median duration = 5 days in males; median duration = 4 days in females).

Overall, most fractures were due to falls (81.0% in males and 80.2% in females; Table 2 ). Falls occurred mainly indoors (73.4% in males and 81.7% in females). The proportion of vertebral fractures due to falls decreased to 46.6% in males and 51.4% in females; a more important role was played by other non-fall reasons such as no apparent cause, lifting heavy objects and bumps (50.9% in males and 43.1% in females).

The three most frequent comorbidities for males overall were hyperlipemia (45.9%), hypertension (38.2%), and ischemic stroke (34.3%) ( Table 3 ). Among females, the three most frequent comorbidities overall were hyperlipemia (47.1%), hypertension (41.6%) and T2DM (21.5%). For both sexes, hyperlipemia was the most frequent comorbidity in both single and multi-site fractures. Patients with one comorbidity were the most common, which included 31.0% of males and 34.9% of females. Three or more comorbidities were seen in 26.1% of males and 20.0% of females. For males, the prevalence of ischemic stroke and T2DM differed between fracture sites. Hypertension, T2DM, ischemic stroke and respiratory diseases showed significant differences between fracture sites in females.

Among hip fracture patients, 44.4% males and 56.2% females underwent replacement surgeries while 37.2% males and 28.2% females underwent internal fixation surgeries ( Table 4 ). For vertebral fractures, the major treatment for patients was percutaneous kyphoplasty (PKP) (44.8% in males, 61.3% in females). Internal fixation was the major treatment for forearm, humerus and multi-site fractures in both sexes.

The major AM in fracture patients was zoledronic acids in males and females ( Table 4 ). Hospitalized vertebral fractures had the highest proportion of AM use (13.8% in males, 25.7% in females).