The Effects of Vitamin D Supplementation and 25-Hydroxyvitamin D Levels on the Risk of Myocardial Infarction and Mortality.

Objective: The aim of the study was to examine the effects of the vitamin D (Vit-D) treatment and nontreatment on Vit-D-deficient patients without a prior history of myocardial infarction (MI).

Materials And Methods: This was a retrospective, observational, nested case-control study of patients (N = 20 025) with low 25-hydroxyvitamin D ([25-OH]D) levels (<20 ng/mL) who received care at the Veterans Health Administration from 1999 to 2018. Patients were divided into 3 groups: Group A (untreated, levels ≤20 ng/mL), Group B (treated, levels 21-29 ng/mL), and Group C (treated, levels ≥30 ng/mL). The risk of MI and all-cause mortality were compared utilizing propensity score-weighted Cox proportional hazard models.

Results: Among the cohort of 20 025 patients, the risk of MI was significantly lower in Group C than in Group B (hazard ratio [HR] 0.65, 95% CI 0.49-0.85,  = .002) and Group A (HR 0.73, 95% CI 0.55-0.96),  = .02). There was no difference in the risk of MI between Group B and Group A (HR 1.14, 95% CI 0.91-1.42,  = 0.24). Compared with Group A, both Group B (HR 0.59, 95% CI 0.54-0.63,  < .001) and Group C (HR 0.61, 95% CI 0.56-0.67,  < .001) had significantly lower all-cause mortality. There was no difference in all-cause mortality between Group B and Group C (HR 0.99, 95% CI 0.89-1.09,  = .78).

Conclusions: In patients with Vit-D deficiency and no prior history of MI, treatment to the (25-OH)D level of >20 ng/mL and >30 ng/mL was associated with a significantly lower risk of all-cause mortality. The lower risk of MI was observed only in individuals maintaining (25-OH)D levels ≥30 ng/mL.