Can monthly vitamin D supplementation decrease the risk of experiencing a major cardiovascular event?
In this large study of more than 21,000 older participants (aged 60 to 84 years), taking 60,000 IU vitamin D each month slightly reduced their likelihood of experiencing a major cardiovascular event (number needed to treat = 172 over 5 years). The benefit is small but aligns with benefits seen with other preventive measures (and was additive to those already used by patients). Side effects were similar among the participants who took vitamin D and those who took placebo. The supplementation does not reduce the risk of mortality over 5 years. 1b
Plan de l'etude:
Randomized controlled trial (double-blinded)
This paper is just one of several reports of the D-Health Trial, a study evaluating the possible benefit of monthly vitamin D supplementation in older people from across most of the continent of Australia. The researchers invited all people between the ages of 60 years to 84 years to participate unless they were already taking vitamin D or had contraindications (history of kidney stones, hyperparathyroidism, and so forth). The 21,315 participants were randomly assigned, using concealed allocation, to receive placebo or 60,000 IU of vitamin D3 (cholecalciferol) monthly for up to 5 years. Participants received monthly reminders to take the treatment. Approximately 35% of participants were taking a statin, 46% were taking a cardiovascular treatment of some sort, 42% had a self-reported history of hypertension, and 22% had a self-reported history of some other cardiovascular disease.
Using intention-to-treat analysis, over 5 years, a cardiovascular event was experienced by 6.6% of the participants who took placebo and 6.0% who took vitamin D, a nonsignificant difference. However, when removing the patients who died because of a noncardiac reason, there were 5.8 fewer major cardiovascular events per 1000 participants in the vitamin D group (95% CI -12.2 to 0.5), resulting in a number needed to treat to avoid one major cardiovascular event of 172 over 5 years. Stroke risk was unaffected, but the likelihood of experiencing a myocardial infarction (hazard ratio [HR] 0.81; 95% CI 0.67 - 0.98) and coronary revascularization (HR 0.89; 0.78 - 1.01) was lower in the vitamin D group. Adverse effects were similar in both groups.
Allen F. Shaughnessy, PharmD, MMedEd
Professor of Family Medicine