Low vitamin D levels associated with increased mortality

From a recent study published in Mayo Clinic Proceedings:

Objective

To determine the relationship between 25-hydroxyvitamin D (25[OH]D) values and all-cause and cause-specific mortality.

Patients and Methods

We identified all serum 25(OH)D measurements in adults residing in Olmsted County, Minnesota, between January 1, 2005, and December 31, 2011, through the Rochester Epidemiology Project. All-cause mortality was the primary outcome. Patients were followed up until their last clinical visit as an Olmsted County resident, December 31, 2014, or death. Multivariate analyses were adjusted for age, sex, race/ethnicity, month of measurement, and Charlson comorbidity index score.

Results

A total of 11,022 individuals had a 25(OH)D measurement between January 1, 2005, and December 31, 2011, with a mean ± SD value of 30.0±12.9 ng/mL. Mean age was 54.3±17.2 years, and most were female (77.1%) and white (87.6%). There were 723 deaths after a median follow-up of 4.8 years (interquartile range, 3.4-6.2 years). Unadjusted all-cause mortality hazard ratios (HRs) and 95% CIs for 25(OH)D values of less than 12, 12 to 19, and more than 50 ng/mL were 2.6 (95% CI, 2.0-3.2), 1.3 (95% CI, 1.0-1.6), and 1.0 (95% CI, 0.72-1.5), respectively, compared with the reference value of 20 to 50 ng/mL. In a multivariate model, the interaction between the effect of 25(OH)D and race/ethnicity on mortality was significant (P<.001). In white patients, adjusted HRs for 25(OH)D values of less than 12, 12 to 19, 20 to 50, and greater than 50 ng/mL were 2.5 (95% CI, 2.2-2.9), 1.4 (95% CI, 1.2-1.6), 1.0 (referent), and 1.0 (95% CI, 0.81-1.3), respectively. In patients of other race/ethnicity, adjusted HRs were 1.9 (95% CI, 1.5-2.3), 1.7 (95% CI, 1.1-2.6), 1.5 (95% CI, 1.0-2.0), and 2.1 (95% CI, 0.77-5.5).

Conclusion

White patients with 25(OH)D values of less than 20 ng/mL had greater all-cause mortality than those with values of 20 to 50 ng/mL, and white patients had greater mortality associated with low 25(OH)D values than patients of other race/ethnicity. Values of 25(OH)D greater than 50 ng/mL were not associated with all-cause mortality.