Total 25-hydroxyvitamin D concentration as a predictor for all-cause death and cardiovascular event risk among ethnic Chinese adults: A cohort study in a Taiwan community

Background: Evidence of an inverse association between serum 25-hydoroxyvitamin D [25(OH)D] and the risk of all-cause death and cardiovascular disease from prospective studies is inconsistent. We tested the relationship between 25(OH)D and the risk among adult ethnic Chinese in Taiwan. Methods: We conducted a community-based cohort study of 1816 participants (age 60.2±10.2 yrs, 45.0% women) in the Chin-Shan Community Cardiovascular Cohort Study who were free of cardiovascular diseases at baseline and provided 25(OH)D measurements. Results: During a median 9.6 (interquartile range, 8.8-10.5) years' follow-up period, totally 263 cases developed cardiovascular death events and 559 participants were documented to death from any cause. As 25(OH)D concentration increased, the incidence rates of cardiovascular events and all-cause death decreased progressively. 25(OH)D was inversely associated with all-cause death: the adjusted hazard ratio was 0.49 (95% confidence interval [CI], 0.25-0.97) for the third quartile and a significant J-shape relationship was found. The performance measures by integrated discriminative improvement showed significant improvement after adding 25(OH)D information (0.14%, 95% CI, 0.03-0.31, P=0.050, for all-cause death and 0.32%, 95% CI, 0.02-0.62, P=0.018 for cardiovascular events). Conclusion: These findings suggested a modest inverse association between 25(OH)D and the risk of all-cause death among diabetic participants and a good predictive factor in the community. Further studies to investigate the mechanism of vitamin D role on health effect are warranted.