The clinical outcomes of selenium supplementation on critically ill patients A meta-analysis of randomized controlled trials

Purpose: Selenium supplementation is a potentially promising adjunctive therapy for critically ill patients, but the results are controversy among studies. Accordingly, we performed this meta-analysis to more clearly detect the efficacy and safety of selenium supplementation on critically ill patients. Methods: Systematic literature retrieval was carried out to obtain RCTs on selenium supplementation for critically ill patients up to August 2017. Data extraction and quality evaluation of these studies were performed by 2 investigators. Statistical analyses was performed by RevMan 5.3. Trial sequential analysis (TSA) was conducted to control the risks of type I and type II errors and calculate required information size (RIS). Results: Totally 19 RCTs involving 3341 critically ill patients were carried out in which 1694 participates were in the selenium supplementation group, and 1647 in the control. The aggregated results suggested that compared with the control, intravenous selenium supplement as a single therapy could decrease the total mortality (RR= 0.86, 95% CI: 0.78-0.95, P=. 002, TSA-adjusted 95% CI= 0.77-0.96, RIS= 4108, n= 3297) and may shorten the length of stay in hospital (MD -2.30, 95% CI -4.03 to -0.57, P=. 009), but had no significant treatment effect on 28-days mortality (RR= 0.96, 95% CI: 0.85-1.09, P=. 54) and could not shorten the length of ICU stay (MD -0.15, 95% CI -1.68 to 1.38, P=. 84) in critically ill patients. Our results also showed that selenium supplementation did not increase incidence of drug-induced side effect compared with the control (RR 1.04, 95% CI 0.83 to 1.30, P=. 73). Conclusions: The current evidence suggests that the use of selenium could reduce the total mortality, and TSA results showed that our outcome is reliable and no more randomized controlled trials are needed. But selenium supplementation might have no effect on reducing 28-days mortality as well as the incidence of new infections, or on length of stay in ICU or mechanical ventilation. However, the results should be used carefully because of potential limitations.