Publication Details

Title :

Association of protein intake with the outcomes of critically ill patients: a post hoc analysis of the PermiT trial


Current Research in Translational Medicine

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Arabi YM1,2, Al-Dorzi HM1,2, Mehta S3, Tamim HM1,2,4, Haddad SH2, Jones G5, McIntyre L5, Solaiman O6, Sakkijha MH2, Sadat M1,2, Afesh L1,2, Kumar A7, Bagshaw SM8, Aldawood AS1,2; PermiT Trial Group.


1 College of Medicine, King Saud Bin Abdulaziz University for Health Sciences, King Abdullah International Medical Research Center.

2 Intensive Care Department, King Abdulaziz Medical City, Riyadh, Kingdom of Saudi Arabia.

3 Department of Medicine and Interdepartmental Division of Critical Care Medicine, Mount Sinai Hospital and University of Toronto, Toronto, Ontario, Canada.

4 Department of Internal Medicine, American University of Beirut Medical Center, Beirut, Lebanon.

5 Department of Medicine, Division of Critical Care Medicine, University of Ottawa, Ottawa Hospital Research Institute, Ottawa, Canada.

6 King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia.

7 Health Sciences Center, Manitoba, Canada.

8 Department of Critical Care Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada.

Year of Publication:






The optimal amount of protein intake in critically ill patients is uncertain.


In this post hoc analysis of the PermiT (Permissive Underfeeding vs. Target Enteral Feeding in Adult Critically Ill Patients) trial, we tested the hypothesis that higher total protein intake was associated with lower 90-d mortality and improved protein biomarkers in critically ill patients.


In this post hoc analysis of the PermiT trial, we included patients who received enteral feeding for ≥3 consecutive days. Using the median protein intake of the cohort as a cutoff, patients were categorized into 2 groups: a higher-protein group (>0.80 g • kg-1 • d-1) and a lower-protein group (≤0.80 g • kg-1 • d-1). We developed a propensity score for receiving higher protein. Primary outcome was 90-d mortality. We also compared serial values of prealbumin, transferrin, 24-h urinary nitrogen, and 24-h nitrogen balance on days 1, 7, and 14.


Among the 729 patients included in this analysis, the average protein intake was 0.8 ± 0.3 g • kg-1 • d-1 [1.0 ± 0.2 g • kg-1 • d-1 in the higher-protein group (n = 365) and 0.6 ± 0.2 g • kg-1 • d-1 in the lower-protein group (n = 364); P < 0.0001]. There was no difference in 90-d mortality between the 2 groups [88/364 (24.2%) compared with 94/363 (25.9%), propensity score-adjusted OR: 0.80; 95% CI: 0.56, 1.16; P = 0.24]. Higher protein intake was associated with an increase in 24-h urea nitrogen excretion compared with lower protein intake, but without a significant change in prealbumin, transferrin, or 24-h nitrogen balance.


In the PermiT trial, a moderate difference in protein intake was not associated with lower mortality. Higher protein intake was associated with increased nitrogen excretion in the urine without a corresponding change in prealbumin, transferrin, or nitrogen balance. Protein intake needs to be tested in adequately powered randomized controlled trials targeting larger differences in protein intake in high-risk populations.