Association between probiotics and 28-day mortality in critically ill adults: A retrospective cohort study.

BACKGROUND: The gut microbiota plays a crucial role in the human microenvironment, and critically ill patients often experience gut microbiota dysbiosis. Although probiotics have been reported to improve clinical outcomes, evidence regarding their effect on mortality remains inconsistent. Furthermore, no study has examined whether probiotic administration influences the development of persistent inflammation, immunosuppression, and catabolism syndrome (PICS). METHODS: This retrospective cohort study analyzed adult patients admitted to intensive care units using a claims database. Patients who received any probiotics between Days 1 and 3 were defined as the probiotics group, and the others as the comparator group. A propensity score-matched analysis was conducted. The primary outcome was 28-day mortality, and the secondary outcomes were PICS on Days 28 and 14, and other clinical indicators. RESULTS: A total of 79,243 patients were included in the analysis, and 3730 matched pairs were generated. After matching, 28-day mortality was lower in the probiotics group than in the no-probiotics group (6.3% vs. 7.9% in the first dataset; pooled risk difference [95% confidence interval], -1.6% [-3.0% to -0.3%]). PICS on Day 28 and Day 14 did not significantly differ between the groups. CONCLUSIONS: In the present study, the early administration of probiotics to intensive care unit patients was associated with a lower incidence of 28-day mortality, but not with PICS on Days 28 or 14. These findings suggest that probiotics for critical illness may provide more benefits than risks.