Probiotics' effects on the incidence of nosocomial pneumonia in critically ill patients: a systematic review and meta-analysis

Introduction: To evaluate the efficacy of probiotics in preventing nosocomial pneumonia in critically ill patients. Methods: We searched PubMed, EMBASE, and the Web of Science for relevant studies. Two reviewers extracted data and reviewed the quality of the studies independently. The primary outcome was the incidence of nosocomial pneumonia. Study-level data were pooled using a random-effects model when I-2 was > 50% or a fixed-effects model when I-2 was < 50%. Results: Twelve randomized controlled studies with a total of 1,546 patients were considered. Pooled analysis showed a statistically significant reduction in nosocomial pneumonia rates due to probiotics (odd ratio [OR]= 0.75, 95% CI 0.57 to 0.97, P = 0.03, I-2 = 46%). However, no statistically significant difference was found between groups regarding in-hospital mortality (OR = 0.93, 95% CI 0.50 to 1.74, P = 0.82, I-2 = 51%), intensive care unit mortality (OR = 0.84, 95% CI 0.55 to 1.29, P = 0.43, I-2 = 0%), duration of stay in the hospital (mean difference [MD] in days = -0.13, 95% CI -0.93 to 0.67, P = 0.75, I-2 = 46%), or duration of stay in the intensive care units (MD = -0.72, 95% CI -1.73 to 0.29, P = 0.16, I-2 = 68%). Conclusions: The use of probiotics was associated with a statistically significant reduction in the incidence of nosocomial pneumonia in critically ill patients. However, large, well-designed, randomized, multi-center trials are needed to confirm any effects of probiotics clinical endpoints such as mortality and length of ICU and hospital stay.