To summarize the evidence on the associations between 25-hydroxyvitamin D (25(OH)D) and risk of mortality in patients with chronic kidney disease (CKD). A comprehensive search of PubMed, Scopus, Web of Science, and Google Scholar for relevant papers published up to November 2025 that assessed the association between serum vitamin D levels and the risk of all-cause, cardiovascular disease (CVD), non-CVD, and cancer mortality was conducted. The lowest-versus-highest analysis and the linear and non-linear dose-response analyses were performed using a random-effects model. Overall, 36 publications (35 studies) with a total sample size of 129,135 participants, aged between 18 and 90 years, were included in the current meta-analysis. During the follow-up periods ranging between 3 months and 18 years, 117,403 cases of all-cause mortality, 2,568 cases of CVD mortality, 886 cases of non-CVD mortality, and 289 cases of cancer mortality were identified. The summary relative risk (RR) and 95% confidence intervals (CIs) comparing lowest versus highest levels of 25(OH)D was 1.61 (95% CI: 1.41–1.84, I2 = 89%, n = 28 studies, very low certainty) for all-cause mortality, 1.68 (95% CI: 1.41-2.00, I2 = 20%, n = 9, very low certainty) for CVD mortality, 1.33 (95% CI: 0.94–1.89, I2 = 26%, n = 3, very low certainty) for non-CVD mortality, and 1.51 (95% CI: 1.09–2.09, I2 = 26%, n = 1, very low certainty) for cancer mortality. There was evidence of non-linearity in the analysis of all-cause and CVD mortality, with a greater reduction in risk from serum levels of 12.5 nmol/L up to 60 nmol/L compared to higher levels, but with slight further reductions in risk with serum levels up to 110 nmol/L. This meta-analysis provides further evidence that lower levels of 25(OH)D are associated with a higher risk of all-cause, CVD, and cancer mortality in CKD patients. However, all outcomes were graded as very low certainty, and the observed associations may be influenced by confounding, small-study effects, and wide prediction intervals that include the null. Observed low-risk range around ~ 60 nmol/L in the non-linear dose-response analyses, should be interpreted cautiously and requires validation in randomized controlled trials. The protocol for this review was registered in PROSPERO (2025 CRD42025105350).
Hacheso et al. (Wed,) studied this question.