Inflammatory score, intrinsic capacity and the risk of new-onset chronic lung disease: a cohort study from the China Health and Retirement Longitudinal Study

Background: Chronic lung disease (CLD) presents a substantial health challenge among aging populations. Currently, the roles of intrinsic capacity (IC) and inflammatory score (IS) in the development of CLD remain to be fully elucidated. This study aimed to investigate the associations of IC and IS with the risk of CLD in older adults. Methods: This study analyzed data from 5,425 participants aged 45 years and older without CLD at baseline, drawn from the nationally representative China Health and Retirement Longitudinal Study (CHARLS). Participants were followed from 2011 to 2015. Assessment of IC covered six domains according to standardized guidelines. An IS was derived by summing standardized C-reactive protein (CRP) and white blood cell (WBC) values from fasting samples. The associations of IC and IS with new-onset CLD were analyzed using generalized linear models (GLMs), adjusting for demographic, socioeconomic, and behavioral covariates. Results: Among 5,425 participants (mean age 57.8 years; 49.9% women), 316 (5.8%) developed CLD during follow-up. An elevated IS was significantly associated with a higher risk of new-onset CLD, with participants in the highest quartile exhibiting 38% greater odds compared to the lowest quartile after full adjustment [odds ratio (OR) =1.38, 95% confidence interval (CI): 1.01-1.90]. Conversely, IC showed a strong protective effect, with each unit increase linked to a 20% reduction in CLD risk (OR =0.80, 95% CI: 0.73-0.88) in fully adjusted models. Dose-response analyses confirmed linear associations for both markers. Conclusions: The results indicate that greater IC corresponds to a reduced likelihood of developing new-onset CLD, whereas elevated systemic inflammation is linked to an increased risk of new-onset CLD.