The use of activated vitamin D and risks of hospitalization for infection and amputation in incident hemodialysis patients in Taiwan: a nationwide population-based cohort study

BACKGROUND: Hemodialysis patients have a high risk of mortality. The most common causes of death are cardiovascular disease and infection. The potential hazard or benefit associated with vitamin D use and cardiovascular or infection outcome is poorly characterized. METHODS: We conducted a retrospective observational cohort study by recruiting 52,757 patients older than 20 years from Taiwan National Health Insurance Research Database (NHIRD) who initiated maintenance hemodialysis between 2001 and 2009. Patients who were prescribed activated vitamin D before the 360th day from hemodialysis initiation were defined as vitamin D users. The primary outcome of interest includes occurrence of acute myocardial infarction (AMI), ischemic stroke, lower limb amputation, and hospitalization for infection, respectively, while death events are treated as competing events. We conducted competing risk analysis using subdistribution hazard regression model to estimate subdistribution hazard ratios (SHRs) in relation to various outcomes. RESULTS: During the median follow-up of 1019 days, the vitamin D users had a lower crude mortality rate, lower incidences of AMI, ischemic stroke, amputation, and hospitalization for infection compared with non-users. Taking into consideration competing events of death, vitamin D users were associated with a lower hazard of lower limb amputation (SHR 0.84 [95% CI, 0.74–0.96]) and hospitalization for infection (SHR 0.90 [95% CI, 0.87–0.94]), but not AMI or ischemic stroke, after adjustment for potential confounders. Subgroup analyses and dose response evaluation both showed a consistent association of activated vitamin D treatment with decreased risk of amputation and infection. CONCLUSION: The findings suggest that therapeutic activated vitamin D use in hemodialysis patients may be beneficial for decreasing infection events and amputation, of which the latter is a complication of peripheral vascular disease, rather than reducing major atherosclerotic cardiovascular events such as AMI or ischemic stroke.