Effect of PROtein-calorie MalnutritiOn on clinical ouTcomEs in AKI patients on CRRT: A secondary analysis of a prospective cohort study (PROMOTE-CRRT)

Protein–calorie malnutrition is common among critically ill patients with acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT). These patients experience heightened metabolic stress and substantial amino acid and protein losses through CRRT, predisposing them to nutritional deficits. Despite existing recommendations of 1.0-1.5 g/kg/day of protein and 20–30 kcal/kg/day energy intake, achieving these targets remains challenging due to frequent feeding interruptions, haemodynamic instability, and metabolic complications. However, evidence linking nutritional provision to outcomes in this population remains limited. This study aimed to evaluate the association between delivered energy and protein intake and mortality among AKI patients receiving CRRT.

We conducted a secondary analysis of the prospective VExLUS-KRT study at the King Chulalongkorn Memorial Hospital from December 01, 2023, to November 30, 2025 (NCT06254703). The study included critically ill adult patients with AKI who underwent CRRT. Demographic, clinical, and nutritional data were prospectively collected. Protein and calorie intakes were calculated daily from enteral, parenteral, and intravenous sources including dextrose, propofol and citrate infusion. The effluent urea nitrogen was collected daily and used to calculate normalised protein catabolic rate (nPCR). The primary objective was to determine the association between protein–calorie intake and 28-day all-cause mortality 

A total of 100 eligible patients were analysed. The median age was 67 years, and 64% had BMI < 25 kg/m². The 28-day mortality rate was 54%. Compared with survivors, non-survivors had significantly lower total calorie intake (median 15.8 (interquartile range (IQR) 10.3-25.3) vs 24.8 (IQR 16.1-33.1) kcal/kg/day, p = 0.001) and protein intake (0.48 (IQR 0-0.8) vs 0.72 (IQR 0.38-0.91) g/kg/day, p = 0.009). Patients who achieved ≥20 kcal/kg/day had lower 28-day mortality (37.2% vs 71.4%, p = 0.001) and in-hospital mortality (52.9% vs 81.6%, p = 0.002) and more ICU-, RRT-, ventilator- and vasopressor-free days (p <0.001, 0.046, <0.001, respectively) than those with <20 kcal/kg/day. There was a U-shaped relationship between between protein intake and 28-day mortality, with the highest mortality in patients who received protein <0.5 g/kg/d (HR 3.48 (95% CI 1.76-6.9); p<0.001). Patients who received <20 kcal/kg/day and protein <1.2 g/kg/d were independently associated with increased risk of 28-day mortality (hazard ratio 3.18 (95% CI 1.72-5.88), p<0.001), after adjusting for mNUTRIC and sex, compared to those with high calorie/low protein intake and high calorie/high protein intake (log rank p = 0.002). Non-survivors had a significantly higher and increasing BUN/Cr ratio over time compared to survivors (p<0.001), suggesting higher catabolic state. There was a moderate positive correlation between protein intake and normalized protein catabolic rate (nPCR) (Spearman’s r = 0.42, p < 0.001).

In critically ill patients with AKI and CRRT, inadequate protein and calorie intake were associated with higher mortality. These findings highlight the importance of adequate nutritional support during CRRT and inform future interventional studies in this area.