To investigate the association between five-time chair stand test (CST) performance and the risk of incident chronic lung disease (CLD) in middle-aged and older adults, and to explore its clinical significance for early risk identification in community populations.

Data were obtained from the China Health and Retirement Longitudinal Study (CHARLS). A total of 10, 371 participants aged ≥45 years at baseline (2011) who were free of CLD and had complete data on key variables were included, with follow-up waves in 2013, 2015, 2018, and 2020. Participants were categorized into an abnormal CST group (n=4 668, male CST>7.5 s, female CST>9.5 s) and a normal CST group (n=5 703, male CST ≤7.5 s, female CST ≤9.5 s). Kaplan-Meier curves and log-rank tests were used to compare cumulative CLD incidence between groups, and Cox proportional hazards models were employed to estimate hazard ratios (HR) and 95% confidence intervals (CI).

During follow-up, 1, 601 out of 10, 371 participants developed incident CLD, including 870 cases (18.64%) in the abnormal CST group and 731 cases (12.82%) in the normal CST group. Compared with the normal group, the abnormal group was older and had higher proportions of females, rural residents, unmarried individuals, those with lower educational levels, and those with hypertension, diabetes, heart disease, stroke, and related medication use (all P<0.05). Receiver operating characteristic (ROC) analysis showed that for males, the area under the curve (AUC) of CST for predicting incident CLD was 0.588 (95%CI: 0.567~0.610), with an optimal cut-off value of 7.5 s, sensitivity of 68.35%, and specificity of 44.96%; for females, the AUC was 0.583 (95%CI: 0.561~0.604), with an optimal cut-off value of 9.5 s, sensitivity of 41.33%, and specificity of 71.50%. Kaplan-Meier curves demonstrated that the abnormal CST group had a significantly lower event-free survival rate than the normal group (log-rank P<0.001). Cox regression showed that in the unadjusted model, abnormal CST was associated with an increased risk of incident CLD (HR=1.509, 95%CI: 1.368~1.665, P<0.001); after adjusting for demographic factors, lifestyle, comorbidities, and medication use, the association remained robust (HR=1.559, 95%CI: 1.402~1.733, P<0.001).

Baseline CST abnormality is a predictor of increased risk of incident CLD in middle-aged and older adults. It holds clinical significance for population-level risk stratification and early community-based identification.