The effect of selenium therapy in critically ill patients: an umbrella review of systematic reviews and meta-analysis of randomized controlled trials

Background: Selenium is an essential nutrient with antioxidant, anti-inflammatory, and immuno-regulatory properties. Studies have displayed that in critically ill patients, selenium supplementation may be a potentially promising adjunctive therapy. Objective: We aimed to present an overview of the effects of selenium supplementation in adult critically ill patients based on published systematic reviews and meta-analyses (SRMAs) of randomized controlled trials (RCTs). Methods: A literature search in three electronic databases, PubMed, Scopus, and Web of Science, was performed to find eligible SRMAs until July 2022. For each outcome, the risk ratios (RRs) or mean differences (MDs) and 95% confidence intervals (CIs) were recalculated using either random or fixed effect models. The methodological quality and quality of evidence of the SRMAs were assessed by applying "A Measurement Tool to Assess Systematic Reviews" (AMSTAR2) and Grading of Recommendations Assessment, Development, and Evaluation(GRADE) tools, respectively. Results: We included 17 meta-analyses containing 24 RCTs based on inclusion criteria. Selenium supplementation can reduce the incidence of mortality (RR: 0.83, 95% CI 0.71, 0.98, P = 0.024) and incidence of acute renal failure (RR: 0.67, 95% CI 0.46, 0.98, P: 0.038) significantly; however, the certainty of evidence was low. Moreover, with moderate to very low certainty of evidence, no significant effects were found for risk of infection (RR: 0.92, 95% CI 0.80, 1.05, P: 0.207), pneumonia (RR: 1.11, 95% CI 0.72, 1.72, P: 0.675), as well as the length of ICU (MD: 0.15, 95% CI - 1.75, 2.05, P: 0.876) and hospital stay (MD: - 0.51, 95% CI - 3.74, 2.72, P: 0.757) and days on ventilation (MD: - 0.98, 95% CI - 2.93, 0.98, P: 0.329). Conclusions: With low quality of evidence, the use of selenium supplementation could improve the risk of mortality and acute renal failure, but not other outcomes in critically ill patients.