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.
Patients aged 18 years or older admitted to the ICU.
Patients receiving exclusive enteral or parenteral nutrition
Acute kidney injury or exacerbated chronic kidney disease according to KDIGO criteria (increase in creatinine greater than 0.3 mg/dL in less than 48 hours or a 1.5-fold increase in baseline creatinine in 7 days)
Patients diagnosed with chronic kidney disease with a creatinine clearance of less than 30 ml/min/m2 or on dialysis at admission.
Patients with a history of kidney transplantation
Patients with severe liver disease (Child-Pugh score >7 points)
Patients with acute kidney injury undergoing renal replacement therapy at T0
The study population consists of critically ill adult patients (≥18 years) admitted to intensive care units at five tertiary hospitals in Argentina. Eligible patients are those receiving exclusive enteral or parenteral nutrition who present with acute kidney injury (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 hemodialysis at admission, previous kidney transplant, severe liver disease, or body mass index (BMI) \>30 are excluded.
Cohort
Retrospective
Not listed
Time to recovery of kidney function
Recovery of kidney function will be defined as the serum creatinine returning to ≤1.5 times the baseline value or ≤30% above the baseline value, with death considered a competing event. The analysis will compare patients receiving ≤1.2 g/kg/day vs. \>1.2 g/kg/day of protein intake on ICU day 5.
Change in blood urea levels at day 14
Comparison of serum urea concentration between groups at day 14 after ICU day 5 (Time Zero). The outcome will assess whether patients with higher protein intake (\>1.2 g/kg/day) show different urea values compared with those with standard intake (≤1.2 g/kg/day).
ICU length of stay
Comparison of the duration of ICU stay between groups classified by protein intake on day 5 of ICU stay. Discharge will be considered the endpoint, with death treated as a competing event in the analysis.
Mortality at 30 days
Proportion of patients who die within 30 days. The outcome will compare mortality rates between patients with higher protein intake (\>1.2 g/kg/day) and those with standard intake (≤1.2 g/kg/day).
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