Comparison of two isocaloric parenteral nutrition regimens with different protein content - A propensity-score matched comparative study.

Introduction: Objective: this study aimed to assess the effects of two isocaloric parenteral nutrition (PN) regimens with different protein content and non-protein calorie to nitrogen ratio (NPCNR) on the evolution of nutritional parameters and outcomes in adult inpatients. Methods: this was a retrospective quasi-experimental study performed in a 400-bed tertiary hospital. Adult inpatients were initially eligible if they had received ≥ 4 days of PN with NPCNR ≥ 100 or ≤ 90 in a period of three years. Patients were propensity-score matched to adjust for differences, resulting in two final cohorts: Cohort "Medium-P" included patients receiving PN with NCPCNR ≥ 100 and cohort "High-P", receiving PN with NCPCNR ≤ 90. The main variables were differences in plasma albumin, prealbumin, cholesterol, and lymphocyte count, days requiring PN, length of stay, and mortality at 90 days. Results: 202 patients were finally recruited and divided into the two equal cohorts. Patients were mainly male (122; 60.4 %), surgical (149; 73.8 %), critically ill (100; 49.5 %), with high nutritional risk (141; 69.8 %) and with a neoplasm (145; 71.8 %). PN provided 25 kcal/kg/day, but protein intake was 0.25 g/kg/day higher in the "High-P" cohort. Baseline characteristics and biochemistry were not different between the two cohorts. The "High-P" cohort presented a smaller difference at the end of PN for lymphocytes, more days with hyperglycaemia, and more days requiring PN. The rest of variables did not differ. Conclusions: high doses of protein (lower NPCNR) did not present advantages compared to medium doses of protein (higher NPCNR) when providing isocaloric PN in adult inpatients.