Abstract
BACKGROUND: Vitamin D insufficiency is a prevalent issue in patients suffering from CKD. The purpose of this study was to determine whether serum 25(OH)D levels are associated with all-cause and cardiovascular mortality in patients with CKD. METHODS: To examine the associations between 25(OH)D levels and cardiovascular mortality, this retrospective cohort study used the National Health and Nutrition Examination Survey (NHANES) and the National Death Index (NDI) 2007‒2018 database. A total of 2,668 eligible subjects were included in this study, with follow-up conducted until December 31, 2019. The associations were assessed using Cox proportional hazards regression, restricted cubic splines, Kaplan-Meier survival curves, and competing risks survival analysis. Furthermore, subgroup and sensitivity analyses were performed. RESULTS: During a median follow-up of 72 months in a weighted population of 11,715,452 eligible participants, there were 665 deaths from any cause, including 196 cardiovascular-related deaths. After adjusting for covariates, lower levels of 25(OH)D were significantly associated with increased risks for both all-cause mortality (HR= 0.85, 95 % CI 0.77∼0.94) and cardiovascular mortality (SHR= 0.80, 95 % CI 0.67∼0.94). Consistent results were also observed when analyzing 25(OH)D as a categorical variable (quartile). Compared to group Q1, both group Q3 (HR = 0.71, 95 % CI 0.54‒0.93) and group Q4 (HR = 0.72, 95 % CI 0.55‒0.94) exhibited a significantly reduced mortality risk. Weighted restricted cubic splines revealed an inverse J-shaped linear association between levels of 25(OH) D and all-cause mortality ((PNonliner > 0.05). Subgroup analysis and sensitivity analysis yielded similar findings. CONCLUSIONS: All-cause mortality and cardiovascular disease-related mortality were significantly increased by lower 25(OH)D levels, both as continuous and categorical variables. 25(OH)D has an inverse J-shaped linear association with all-cause and cardiovascular mortality.