Do serum vitamins, carotenoids, and retinyl esters influence mortality in osteoarthritis? Insights from a nationally representative study

Background: The relationship between serum vitamins, carotenoids, and retinyl esters and mortality risk among individuals with osteoarthritis (OA) remains unclear. This study aimed to investigate these associations. Methods: Based on data from NHANES 2001 to 2018 and the National Death Index (NDI), a total of 3,626 patients with OA were included. Cox proportional hazards models were used to evaluate the associations between serum nutrient levels and all-cause, cardiovascular, and cancer mortality. Nonlinear effects were assessed using smooth curve fitting and piecewise regression models. Subgroup analyses, sensitivity analyses, and validation in non-OA populations were conducted. Additionally, interactions between vitamin levels and OA status were examined. Results: Higher levels of vitamin D, retinyl palmitate, and stearic acid were associated with a reduced risk of all-cause mortality in patients with OA, with consistent results in sensitivity analyses. A nonlinear inverse association was observed between vitamin D and all-cause mortality in women, with a threshold at 30.5 nmol/L. Vitamin C was associated with cardiovascular mortality, while retinyl palmitate and stearic acid were linked to a reduced risk of cancer-related death. The protective effect of vitamin D was stronger among individuals with lower educational levels. In the non-OA population, only vitamin D was associated with mortality. Interaction analysis indicated that high vitamin levels may attenuate the adverse impact of OA on mortality risk. Conclusions: Elevated serum levels of vitamin D, retinyl palmitate, and stearic acid may be associated with reduced all-cause and cause-specific mortality among individuals with OA, highlighting their potential role in the management of OA.