Chronic obstructive pulmonary disease (COPD) is a is typical respiratory ailment that is distinguished by long-lasting blockage of the airways and reduced lung function. COPD is listed as the third most typical reason for mortality worldwide, as stated by the World Health Organization (WHO) (1). In those 40 years of age and older, the prevalence of COPD is 10.1%, leading to approximately 3.23 million deaths annually. It’s noteworthy that 80% of these deaths occur in low- and middle-income countries, greatly increasing the burden of sickness and mortality worldwide (2). The primary risk factors for COPD include smoking, air pollution, and genetic predispositions (3, 4). Despite advancements in understanding the pathogenesis of COPD and improvements in clinical diagnosis and treatment strategies, the lack of prominent early symptoms often leads to delayed diagnosis, with many patients only being identified at more advanced stages of the disease (5). Consequently, finding workable solutions for early screening and diagnosis is crucial for enhancing the management and treatment outcomes of COPD patients.

While FEV1/FVC remains the gold standard for COPD diagnosis, its application faces several practical challenges, particularly in resource-limited settings. The test requires patients to exhale forcefully for a prolonged period (often >6 s) to achieve a complete FVC, which can be particularly challenging for elderly patients and those with severe respiratory conditions. This requirement often leads to poor patient compliance and potentially inaccurate results. Additionally, the sophisticated equipment and technical expertise required for accurate FVC measurement may not be readily available in primary healthcare settings or underserved areas.

In contrast, FEV3/FEV6 measurement presents clear clinical advantages. The shorter exhalation time of 6 s, compared to the extended period required for complete FVC, substantially improves patient cooperation and reduces exertion, particularly among elderly patients and those with impaired lung function. The standardized 6-s duration also streamlines the testing procedure, enabling broader implementation across primary healthcare facilities with varying resource levels. Recent research indicates that FEV3/FEV6 demonstrates heightened sensitivity in detecting early-stage COPD when compared to FEV1/FVC, especially in cases of subtle airway obstruction. This enhanced detection capability proves particularly valuable in identifying mild to moderate COPD cases that typically remain undiagnosed until symptoms progress to more severe stages.

Furthermore, the economic implications of implementing FEV3/FEV6 testing are significant. The simpler procedure requires less sophisticated equipment and minimal technical training, potentially reducing healthcare costs while maintaining diagnostic accuracy. This cost-effectiveness is particularly relevant in low- and middle-income countries, where COPD burden is highest but healthcare resources are often limited. The combination of improved patient compliance, simplified testing procedures, and potential economic benefits makes FEV3/FEV6 an attractive alternative for large-scale COPD screening programs, particularly in resource-constrained settings.

The FEV3/FEV6 ratio has attracted attention in clinical research as a new indicator in lung function testing. In lung function testing, measuring forced expiratory volume (FEV) is crucial for evaluating the extent of airflow obstruction. The FEV1/FVC ratio is a well-accepted and accurate way to diagnose COPD. It calculates the volume of air forcibly expelled in 1 sec relative to the total volume of air breathed (6). Still, the application of FEV1/FVC can be challenging in primary healthcare settings or underserved areas due to its complexity. In contrast, FEV3/FEV6, a newer lung function parameter, offers advantages such as simplicity and ease of use. Recent research has focused on its sensitivity and predictive value, highlighting its potential as an effective alternative (7, 8).

Early diagnosis is critical for the effective management of COPD. Accurate early detection can not only help slow disease progression and reduce mortality risk but also significantly enhance quality of life and lower treatment costs. Despite this, early diagnosis of COPD remains challenging. Although the traditional FEV1/FVC ratio is considered the gold standard, its lower detection rate in mild to moderate cases highlights the need for more effective screening and diagnostic methods. The emerging FEV3/FEV6 ratio, with its promising sensitivity and specificity for early COPD diagnosis, warrants further investigation (8–10). Additionally, managing and prognosticating COPD is complex, requiring a thorough assessment of disease severity, complications, and other factors. Currently, there is a lack of straightforward and accurate prognostic indicators. This study proposes FEV3/FEV6 as a potential prognostic factor, aiming to offer a new perspective for the long-term management of COPD.

The clinical value of the FEV₃/FEV₆ ratio stems from its sensitivity to early changes in pulmonary mechanics, particularly those affecting the small conducting airways. In the initial stages of COPD, airway narrowing and inflammation often begin in the peripheral small airways, which are less detectable by conventional FEV₁/FVC measurements. FEV₃ represents expiratory flow up to the third second, encompassing both large and small airway dynamics, while FEV₆ approximates forced vital capacity but requires a shorter, standardized effort. The FEV₃/FEV₆ ratio is thus capable of detecting delayed or incomplete expiratory flow that is characteristic of early airflow limitation and dynamic hyperinflation (11).

Additionally, several studies suggest that a declining FEV₃/FEV₆ ratio correlates with air trapping, increased residual volume, and reduced lung elastic recoil, all of which are hallmarks of progressive COPD (12). These pathophysiological changes have been linked to worsened exercise tolerance, higher exacerbation risk, and poorer long-term outcomes. Therefore, the FEV₃/FEV₆ ratio may not only offer greater sensitivity in the early diagnosis of COPD but also serve as a predictive marker for disease progression, facilitating timely intervention and optimized disease management strategies (13).

This study’s objective is to evaluate the practicality of FEV3/FEV6 in the early diagnosis of mild to moderate COPD and its potential for prognostic assessment. The goal is to enhance our understanding of early screening and prognostic tools for COPD and to provide more accurate diagnostic and treatment strategies for clinical practice.

The main topic of this research is the application value of the FEV3/FEV6 ratio in the early diagnosis and prognosis of mild to moderate COPD. The results demonstrate that FEV3/FEV6 is highly correlated with the conventional lung function index FEV1/FVC. Additionally, FEV3/FEV6 exhibits high sensitivity and specificity for diagnosing mild to moderate COPD. Furthermore, this index also provides valuable insights for predicting the prognosis of COPD patients.

Early diagnosis and intervention are crucial for optimizing illness management and boosting the overall quality of life for patients with chronic diseases. This is especially important for chronic, progressive, and irreversible conditions like COPD. Traditionally, the FEV1/FVC ratio has been used as the gold standard for diagnosing COPD; however, this measure has its limitations (17). For instance, its sensitivity is relatively low in detecting mild to moderate COPD, which can result in missed opportunities for early diagnosis and timely intervention.

As an emerging indicator of lung function assessment, the FEV3/FEV6 ratio has received widespread attention in the last several years due to its simple and rapid operation. In this study, FEV3/FEV6 showed a high correlation with FEV1/FVC, which means that the FEV3/FEV6 ratio may serve as an effective early screening tool for COPD (18). In addition, the specificity and sensitivity of FEV3/FEV6 ratio indicate that it has certain clinical application value in mild to moderate COPD diagnosis. This finding is especially significant for primary hospitals and regions with limited resources, as the measurement of the FEV3/FEV6 ratio is more accessible and easier to implement compared to traditional methods (10). Regarding prognosis, while the sensitivity and specificity of FEV3/FEV6 may not match its diagnostic accuracy, it still offers valuable prognostic insights. This indicates that early lung function assessment using FEV3/FEV6 can aid not only in diagnosing COPD but also in providing partial predictions about disease progression and outcomes. Therefore, the FEV3/FEV6 ratio may be an effective technique for guiding the long-term management of COPD.

There are a few restrictions on this research, however. First, the findings’ capacity to be generalized could be influenced by the very little sample size. Second, the study did not account for all factors that could influence COPD diagnosis and prognosis, such as detailed lifestyle information, occupational exposure, and other environmental factors. Additionally, as the study was conducted at a single center, its findings need validation in a broader population. Future research should explore the use of the FEV3/FEV6 ratio in conjunction with other biomarkers or clinical indicators to enhance the accuracy of early COPD diagnosis and prognosis prediction. Despite these drawbacks, the research provides insightful information about the early diagnosis and management of COPD. The FEV3/FEV6 ratio, being a simple and user-friendly diagnostic tool, shows significant potential for early detection of mild to moderate COPD, improving diagnosis rates, and potentially enhancing patient prognosis through timely intervention. With further in-depth research, the FEV3/FEV6 ratio could become a practical and effective tool for COPD management.

Additionally, the influence of anterior chest wall conformation on spirometric indices such as FEV₆ and FEV₃/FEV₆ warrants further investigation. Previous studies have reported that individuals with anterior chest wall deformities may exhibit disproportionately reduced lung volumes and altered airflow parameters, even in the presence of mild to moderate obstructive disease (19). Although our study did not include an assessment of thoracic morphology, this anatomical factor may affect both the absolute values and interpretability of FEV₃/FEV₆, especially in early disease. Future studies should incorporate chest wall imaging or morphometric assessments to better delineate the relationship between chest conformation and simplified spirometric markers such as FEV₆ and FEV₃/FEV₆.

In summary, FEV3/FEV6 screening demonstrates significant potential for clinical application in the early diagnosis and prognosis assessment of mild to moderate COPD. Due to its simplicity and feasibility, the FEV3/FEV6 ratio should be more widely adopted in future COPD research and clinical practice. This broader use could lead to improved and more efficient medical care for COPD patients.