Physical activity modifies the association of the composite dietary antioxidant index with all-cause mortality in the US osteoarthritis population

BackgroundIt remains unclear how antioxidant intake affects all-cause mortality in osteoarthritis (OA) patients. In this prospective cohort study, we aim to explore the association of the Composite Dietary Antioxidant Index (CDAI) with all-cause mortality and investigate the interaction of physical activity (PA) and CDAI on all-cause mortality in OA populations.MethodsA total of 3,197 adults with OA in the National Health and Nutrition Examination Survey (NHANES) from 2001 to 2018 were included in this study. Death outcomes were obtained from National Death Index (NDI) records. Multivariable Cox regression analyses with cubic spines were applied to estimate the association of CDAI with all-cause mortality. The interaction between CDAI and PA on all-cause mortality was further assessed in stratified analysis and interaction tests.ResultsThe hazard ratios for all-cause mortality were 0.95 (0.77–1.17) for Q2, 0.75 (0.59–0.97) for Q3, and 0.71 (0.55–0.92) for Q4 (P for trend