Inflammatory biomarker score and asthma risk: Longitudinal evidence from Chinese and English aging cohorts

BACKGROUND: Asthma is a prevalent airway disease influenced by various factors. Despite the known association between inflammation and asthma, no study has systematically investigated the relationship between inflammatory scores (INS) and asthma risk. This study explored this longitudinal relationship using two prospective cohorts: the China Health and Retirement Longitudinal Study (CHARLS) and the English Longitudinal Study of Aging (ELSA). METHOD: This study included 8,541 CHARLS and 5,701 ELSA participants. A multivariate-adjusted logistic regression model was used to determine the association between INS and risk of developing asthma. Restricted cubic spline (RCS) methods were employed to explore potential nonlinear relationships. Stratification and interaction tests were performed also conducted. After performing multiple imputations for the missing data, a sensitivity analysis was conducted to verify the robustness of the conclusions. RESULTS: In the fully adjusted model, INS were positively with asthma risk (OR = 1.087, 95% CI: 1.010-1.157). The fully adjusted ELSA model also showed a positive association (OR = 1.055, 95% CI: 1.004-1.108). RCS analyses revealed no significant nonlinear relationship between the INS and asthma. Subgroup analysis of the CHARLS cohort identified interaction effects between INS and asthma risk, particularly when stratified by age and smoking status. CONCLUSION: Higher baseline INS was modestly associated with greater odds of subsequent asthma in both CHARLS and ELSA. These findings suggest a possible role of systemic inflammatory burden in asthma development, although further studies are required to establish causality and clinical relevance.