Permissive Underfeeding or Standard Enteral Feeding in High- and Low-Nutritional-Risk Critically Ill Adults Post Hoc Analysis of the PermiT Trial

Rationale: The optimal nutritional strategy for critically ill adults at high nutritional risk is unclear. Objectives: To examine the effect of permissive underfeeding with full protein intake compared with standard feeding on 90-day mortality in patients with different baseline nutritional risk. Methods: This is a post hoc analysis of the PermiT (Permissive Underfeeding versus Target Enteral Feeding in Adult Critically Ill Patients) trial. Measurements and Main Results: Nutritional risk was categorized by the modified Nutrition Risk in Critically Ill score, with high nutritional risk defined as a score of 5-9 and low nutritional risk as a score of 0-4. Additional analyses were performed by categorizing patients by body mass index, prealbumin, transferrin, phosphate, urinary urea nitrogen, and nitrogen balance.. Based on the Nutrition Risk in Critically Ill score, 378 of 894 (42.3%) patients were categorized as high nutritional risk and 516 of 894 (57.7%) as low nutritional risk. There was no association between feeding strategy and mortality in the two categories; adjusted odds ratio (aOR) of 0.84 (95% confidence interval [CI], 0.56-1.27) for high nutritional risk and 1.01 (95% CI, 0.64-1.61) for low nutritional risk (interaction P = 0.53). Findings were similar in analyses using other definitions, with the exception of prealbumin. The association of permissive underfeeding versus standard feeding and 90-day mortality differed when patients were categorized by baseline prealbumin level (<= 0.10 g/L: aOR, 0.57 [95% CI, 0.31-1.05]; >0.10 and <= 0.15 g/L: aOR, 0.79 [95% CI, 0.42-1.48]; >0.15 g/L: aOR, 1.55 [95% CI, 0.80, 3.01]; interaction P = 0.009). Conclusions: Among patients with high and low nutritional risk, permissive underfeeding with full protein intake was associated with similar outcomes as standard feeding.