An overview of evidence from systematic reviews evaluating early enteral nutrition in critically ill patients: more convincing evidence is needed.

International quality improvement initiatives such as Fast-Hug bring a focus on improving the delivery of early enteral nutrition to critically ill patients, however surveys demonstrate current practice remains variable. One way to reduce variability in practice is to provide strong evidence to convince clinicians to change. The purpose of this overview was to identify current best evidence supporting the delivery of early enteral nutrition in critical illness. We sought high-quality evidence in the form of systematic reviews containing meta-analyses of randomised controlled trials. Two authors independently identified studies and assessed methodological quality. Data sources included Medline, EMBASE and hand-searching of guideline reference lists. The literature search identified five systematic reviews that summarised 30 clinical trials. These systematic reviews focused on acutely hospitalised patients, critical illness, burns, elective intestinal surgery and pancreatitis. Early enteral nutrition significantly reduced mortality in elective intestinal surgery patients (relative risk 0.41, 95% confidence interval 0.18 to 0.93, P = 0.03, I2 = 0.0%) and significantly reduced infectious complications in acutely ill hospitalised patients (relative risk 0.45, 95% confidence interval 0.3 to 0.66, P = 0.00006, heterogeneity P = 0.049). Four of five identified systematic reviews had key methodological quality deficiencies. The results of this overview highlight the variability in the evidence regarding the benefits of early enteral nutrition in critically ill patient populations. The inconsistent delivery to critically ill patients may be explained by the lack of convincing evidence. Better evidence may be needed to reduce the irregularity in the provision of early enteral nutrition to critically ill patients.