The interaction between CCR and disability on the risk of chronic obstructive pulmonary disease: evidence from the China Health and Retirement Longitudinal Study Database

Background Although previous studies have separately examined the association between the serum creatinine to cystatin C ratio (CCR) or disability and chronic obstructive pulmonary disease (COPD), the interaction between these factors and their combined impact on COPD prevalence remains insufficiently explored. Methods Self-reported physician-diagnosed COPD, as measured by the validated CHARLS baseline questionnaire, served as the primary outcome. Logistic regression was utilized to assess the association between CCR, disability, and COPD, as well as to evaluate the interaction between these factors and COPD prevalence. Results. Among the 9,668 participants, 1,835 (19.0%) had a COPD diagnosis. The risk of COPD was significantly higher in the low-level CCR group compared to the high-level CCR group (OR = 1.15, 95% CI: 1.03–1.29, P = 0.014). Similarly, individuals with disability exhibited a significantly higher risk of COPD compared to non-disabled individuals (OR = 1.19, 95% CI: 1.04–1.37, P = 0.013). The co-presence of low-level CCR and disability substantially increased the risk of COPD (OR = 1.60, 95% CI: 1.34–1.91, P < 0.001). Conclusions This study identified low-level CCR and disability as independent risk factors for COPD in middle-aged and older adults in China and demonstrated their synergistic effect in increasing COPD risk. A comprehensive prevention and control strategy that integrates nutritional support, muscle function maintenance, and functional ability interventions is recommended for the clinical management of patients with COPD.