Vitamin D supplementation and mortality among critically ill adults: a systematic review and meta-analysis

Randomized controlled trials have failed to demonstrate the effects of vitamin D supplementation on reducing the mortality rate in critically ill adults. A post hoc study revealed that vitamin D administration was linked to a lower 28-day mortality rate. The purpose of this meta-analysis was to investigate how vitamin D supplementation affects mortality in critically ill adults. The effects of vitamin D supplementation, such as baseline 25-hydroxyvitamin D level, vitamin D supplementation dosage, and vitamin D delivery route, were given special attention in relevant subgroups.

The inclusion criteria for eligible studies were as follows: (1) randomized controlled trials; (2) critically ill adults; (3) the intervention group was given vitamin D or a vitamin D metabolite without any restrictions on type, dosage, duration, or route of administration; and (4). the outcome of mortality in critically ill adults.

Subgroup analysis revealed the following findings: (1) there was a trend toward reduced mortality in critically ill adults whose baseline 25-hydroxyvitamin D level was less than 20 ng/mL (RR = 0.87, p = 0.05, 95% CI = 0.76-1.00, I ² = 31%). Meta-analysis revealed a relative risk of mortality of 0.87, indicating that patients with baseline 25-hydroxyvitamin D level less than 20 ng/mL receiving vitamin D supplementation had a 13% lower risk of death than controls; (2) mortality was significantly reduced in patients who received ≤300,000 IU of vitamin D compared with those who received the placebo, (RR = 0.56, p < 0.0001, 95% CI = 0.42-0.74, I ² = 0%); (3) administration by intramuscular injection or intravenous injection significantly reduced the risk of mortality (RR = 0.59, p = 0.0006, 95% CI = 0.44-0.80, I ² = 0%).

This meta-analysis revealed that vitamin D supplementation significantly reduced mortality in critically ill adult patients, but not all patients benefited. The benefit was observed in three subgroups of patients as below: (1) critically ill adults with baseline 25-hydroxyvitamin D levels below 20 ng/mL; (2) critically ill adults receiving ≤300,000 IU of vitamin D supplementation; (3) critically ill adults receiving the supplement via intramuscular or intravenous injection.

CRD420251152462.