Context and Objectives: Vitamin D plays a key role in maintaining bone health, but evidence for its nonskeletal effects is inconsistent.
This study aims to examine the association between serum 25-hydroxyvitamin D [25(OH)D] levels and all-cause mortality in a large general population cohort.
Design, Participants, and Setting: Using the computerized database of the largest health care provider in Israel, we identified a cohort of subjects 20 years old or older with serum 25(OH)D levels measured between January 2008 and December 2009. Vital status was ascertained through August 2011.
Results: Median follow-up was 28.5 months (interquartile range 23.8-33.5 months); 7,247 of 182,152 participants (4.0%) died.
Subjects who died had significantly lower serum 25(OH)D levels (mean 44.8 +/- 24.2 nmol/liter) than those alive at the end of follow-up (51.0 +/- 23.2 nmol/liter), P < 0.001.
After adjustment for age, gender, ethnicity, and seasonality, the hazard ratio (HR) for all-cause mortality was 2.02 [95% confidence interval (CI) 1.89-2.15] for the lowest serum 25(OH)D quartile (<33.8 nmol/liter) compared with the highest. [Note: a hazard ratio of 1.0 would indicate no difference between groups. The HR of 2.02 for lowest vitamin D group indicates risk of mortality was double that for the highest D group.]
After further adjustment for comorbidity, use of vitamin D supplements and statins, smoking, socioeconomic status, and body mass index, the HR was 1.81 (95% CI 1.69-1.95). This remained, even after adjustment for serum low-density lipoprotein, high-density lipoprotein, calcium level (corrected for serum albumin levels), and glomerular filtration rate, 1.85 (95% CI 1.70-2.01).
The fully adjusted HR associated with being in the second 25(OH)D quartile (33.8-49.4 nmol/liter) was 1.25 (95% CI 1.16-1.34).
Conclusions: All-cause mortality is independently and inversely associated with serum 25(OH)D levels at levels less than 50 nmol/liter.
Source: Journal of Clinical Endocrinology and Metabolism, May 30, 2012. PMID:22648653, by Saliba W, Barnett O, Rennert HS, Rennert G. Department of Community Medicine and Epidemiology, Carmel Medical Center, Clalit Health Services; Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel; Department of Internal Medicine Ha’emek Medical Center, Afula, Israel; Department of Epidemiology and Disease Prevention, Office of the Chief Physician, Clalit Health Services Headquarters, Tel Aviv, Israel. [Email: firstname.lastname@example.org]