Continuous Renal Replacement Therapy and Mortality in Critically Ill Obese Adults

Area of Science:

• Nephrology
• Critical Care Medicine
• Obesity Medicine

Background:

• Outcomes for critically ill adults with obesity undergoing continuous renal replacement therapy (CRRT) are not well understood.
• The influence of CRRT dosage on patient outcomes in this population remains uncertain.

Purpose of the Study:

• To investigate whether obesity confers a survival advantage in critically ill adults with acute kidney injury (AKI) requiring CRRT.
• To determine if the prescribed dose of CRRT predicts mortality in this patient group.

Main Methods:

• Retrospective observational cohort study at an academic medical center.
• Compared 30-day and 90-day mortality between obese (BMI ≥ 30 kg/m²) and nonobese (BMI < 30 kg/m²) critically ill adults with AKI on CRRT.
• Used multivariable regression to assess CRRT dose, indexed by actual body weight (ABW), adjusted body weight (AdjBW), or ideal body weight (IBW), as a predictor of mortality.

Main Results:

• 1033 patients were included; median BMI was 26 kg/m² (nonobese) and 36 kg/m² (obese).
• 30-day mortality was similar (54% vs. 48%, p=0.06), but 90-day mortality was lower in obese patients (62% vs. 55%, p=0.02).
• CRRT dose predicted increased mortality when indexed to ABW or AdjBW (HR 1.2-1.16), but not IBW (HR 1.04).

Conclusions:

• Obese critically ill adults with AKI receiving CRRT demonstrated lower short-term mortality compared to nonobese counterparts.
• Ideal body weight (IBW) indexing appears preferable for optimizing CRRT dosing in obese patients, potentially enhancing safety and effectiveness.