Vitamin D has pleiotropic effects important for the proper functioning of multiple organ systems. We investigated whether serum 25-hydroxy vitamin D (25(OH) D) levels influence hospitalization-free survival in patients with chronic kidney disease.Design and method:
In this prospective study, serum levels of 25 (OH) D were obtained from 210 patients with chronic kidney disease in the winter of 2009. Data regarding hospitalizations were collected over the subsequent 3 years.Results:
Vitamin D deficiency, as defined by a serum 25 (OH) D level below 15 ng/ml, was observed in 76.7% of the patients. The mean 25 (OH) D serum level was 13.6 ± 7.8 ng/ml in predialysis patients (n = 62) and 11.3 ± 6.7 ng/ml in dialysis patients (n = 148). During the follow–up, 107 patients (28 predialysis and 79 dialysis) were hospitalized due to infectious (33.6%), cardiovascular disease (23.4%). The predialysis and dialysis groups were divided into two subgroups based on the median 25 (OH) D serum levels. Kaplan-Meier analysis revealed that the risk of hospitalization was significantly lower in both predialysis and dialysis patients with above median serum 25 (OH) D levels (log rank test; P = 0.043 and 0.002, respectively). Multivariate Cox proportional hazards models also demonstrated that the risk of hospitalization was significantly lower for patients with lower serum 25 (OH) D levels in both the predialysis (hazard ratio [HR] 0.963, 95% confidence interval [CI] 0.93 - 0.99) and dialysis groups (HR 0.955, 95% CI 0.91 - 0.99).Conclusions:
We demonstrated that lower serum 25 (OH) D level predicted poor hospitalization -free survival in both predialysis and dialysis chronic kidney disease patients.