Association of fasting in the first 72 h of intensive care unit stay with outcomes of critically ill patients.

Background: Whether fasting early in critical illness course is acceptable is not clear and high-quality data on this topic are lacking. To generate equipoise for future clinical trials and bring additional data to current literature, we compared outcomes of patients fasted during the first 72 h of intensive care unit (ICU) stay to patients receiving any nutrition support during this period.

Methods: Retrospective cohort study of a medical ICU from a tertiary academic center in Brazil. Adult patients treated between November 2017 and February 2022 with an ICU length of stay of ≥5 days were included. Baseline and daily data were retrieved from the prospectively collected administrative database. We did 1:1 propensity score matching to compare patients fasting for at least 72 h with controls. Primary outcome was hospital mortality and secondary outcomes were other resources' use.

Results: During the study period, 1591 patients were cared for in this ICU, of which 998 stayed ≥5 days. After excluding readmissions and propensity score matching, 93 patients in the fasting group were matched to 93 controls. Hospital mortality was similar between fasting and matched control groups (odds ratio = 1.04; 95% CI = 0.56-1.94; P > 0.99). Secondary outcomes were not different between groups, including length of stay, days on mechanical ventilation, and incidence of new infections.

Conclusion: Withholding nutrition support in the first 72 h of ICU stay was not associated with worse outcomes in this cohort of severe critically ill patients.