Effect of Protein Dosage on Persistent Acute Renal Failure in Critically Ill Patients.

Background: Acute kidney injury (AKI) is common in critically ill patients and is associated with worse outcomes, including longer ICU stay, need for dialysis, and higher mortality. Patients with AKI often experience significant protein and calorie loss due to their illness and medical treatments. Providing the right amount of protein may help maintain muscle mass and improve recovery; however, consuming too much protein could potentially worsen kidney function. Current international guidelines recommend adequate protein intake, but the best dose remains uncertain, especially for patients with AKI. Study Purpose: This research will examine whether patients with AKI who receive a higher protein intake (greater than 1.2 g/kg/day) have different outcomes compared to those who receive a standard or lower protein intake (≤1.2 g/kg/day). The primary outcome is whether a higher protein intake leads to a longer recovery time from AKI or worsens kidney function. Study Design: This is a retrospective, multicenter study using data from five hospitals in Argentina. It is designed as a "target trial emulation," meaning researchers will analyze existing patient data as if it were a randomized clinical trial. Patients will be included on the fifth day of their ICU stay and classified into two groups based on their protein intake on day 5: * Group 1 (Standard Protein): ≤1.2 g/kg/day * Group 2 (High Protein): \>1.2 g/kg/day No additional interventions will be performed; data are collected from medical records. Study Population: The study will include adult patients (≥18 years) admitted to the ICU who are receiving exclusive enteral or parenteral nutrition and have AKI (or worsening chronic kidney disease) according to KDIGO criteria. Patients with advanced chronic kidney disease (creatinine clearance \<30 ml/min/1.73 m²) or undergoing hemodialysis at T0, previous kidney transplant, severe liver disease, or BMI \>30 will be excluded. Outcomes: * Primary Outcome: Time to recovery of kidney function within 30 days, measured by creatinine returning close to baseline values. * Secondary Outcomes: Changes in blood urea levels, duration of renal replacement therapy (hemodialysis), ICU length of stay, and 30-day mortality. Statistical Approach: To minimize bias, the study will use advanced statistical methods, including propensity score weighting, to ensure fair comparison between groups. Competing risks (such as death before kidney recovery) will be taken into account in the analysis. Significance: This study will provide important information about the safety and effectiveness of higher protein intake in critically ill patients with AKI. The findings may help guide nutritional strategies in the ICU, optimize kidney outcomes, and improve patient care.