Objective: A number of observational studies have shown an inverse association between circulating 25-hydroxyvitamin D and total mortality, but a reverse J-shaped association has also been reported. In a large nested case-control study, serum-25-hydroxyvitamin D (s-25(OH)D) was positively associated with incident prostate cancer. Based on the same study population, the primary aim of the present study was to investigate the association between s-25(OH)D and total mortality.
Methods: Men participating in population based health screenings during 1981-1991 and enrolled in a nested case-control study were followed throughout 2007 with respect to all-cause and cause-specific mortality. Hazard ratios (HR) with 95% confidence intervals (CI) were calculated using Cox proportional hazards regression.
Results: In men with prostate cancer (n = 2282), there was a significant inverse association between s-25(OH)D and total mortality after controlling for potential confounders (HR = 1.25 (95% CI 1.05-1.50), s-25(OH)D <50 nmol/l versus s-25(OH)D ≥ 50 nmol/l). The corresponding figure among controls (n = 2147) was HR = 1.15 (95% CI 0.88-1.50) and in the total study population HR = 1.19 (95% CI 1.03-1.38). For cause-specific deaths, we found no significant associations.
Conclusions: In this study population, s-25(OH)D was inversely associated with total mortality during more than two decades of follow-up, despite, as previous reported, high s-25(OH)D was associated with increased risk of prostate cancer.