Analysis of the mediating role of inflammatory markers in the association between COPD and frailty

Frailty is common in chronic obstructive pulmonary disease (COPD), but the contribution of systemic inflammation to its association with laboratory-based frailty is not fully understood. We examined the relationship between COPD and the frailty index based on laboratory tests (FI-Lab) and explored whether inflammatory markers explained part of this statistical association. Two independent datasets were analyzed, including a hospital-based cohort and the National Health and Nutrition Examination Survey (NHANES). FI-Lab was used to assess frailty. hierarchical linear regression, mediation, sensitivity, and subgroup analyses were performed. COPD was associated with higher FI-Lab in both datasets after adjustment for covariates. Several inflammatory markers explained part of this association statistically. Mediation estimates differed between the two datasets, but the overall pattern was similar. Results changed little in sensitivity analyses. Greater statistical mediation was observed in older participants, those with overweight or obesity, men, and ever-smokers, although these subgroup findings were exploratory. COPD was linked to higher FI-Lab in both datasets. Systemic inflammation may partly underlie this statistical association. Prospective studies are needed to clarify the temporal relationship and the potential clinical usefulness of these inflammatory markers.