CRRT vs. Prolonged Intermittent Renal Replacement Therapy in Critically Ill Patients: Comparative Analysis and Clinical Implications of RRT Modalities

Background: Renal replacement therapy (RRT) remains a fundamental intervention in the management of acute kidney injury (AKI), particularly in critically ill patients experiencing hemodynamic instability. Among the available modalities commonly employed, Continuous Renal Replacement Therapy (CRRT) and Prolonged Intermittent Renal Replacement Therapy (PIRRT) may significantly impact clinical outcomes and each offers distinct advantages. Methods: We performed a retrospective comparative cohort study using multivariable logistic regression to evaluate two groups of critically ill patients requiring renal replacement therapy (RRT) under hemodynamic instability. Thirteen patients received Continuous RRT (CRRT) and 43 received Prolonged Intermittent RRT (PIRRT) at Dr. Manuel Gea González General Hospital from February to September 2024. Data included baseline labs at dialysis initiation, severity scores, vasopressor use, and initial hemodynamic status. Primary outcomes were 7- and 30-day mortality; secondary outcome was post-RRT renal recovery. Results: In the multivariable logistic regression analysis, age showed a non-significant association with 7-day mortality (OR: 1.052; p = 0.140). APACHE II was the only significant predictor (OR: 1.232; p = 0.039), with each point increase linked to a 23.2% rise in mortality risk. eGFR (CKD-EPI) demonstrated a non-significant inverse association (OR: 0.957; p = 0.705), and vasopressor use was not significant (OR: 2.74; p = 0.99). Seven-day mortality was 46.2% in CRRT vs. 44.2% in PIRRT (p = 0.542), and 30-day mortality was 53.8% vs. 39.5%, respectively (p = 0.222), with no statistically significant differences. Conclusion: Mortality was slightly higher in the CRRT group (46.2% at 7 days and 53.8% at 30 days) compared to the PIRRT group (44.2% at 7 days and 39.5% at 30 days); however, these differences were not statistically significant (p > 0.05). Among the variables included in the multivariable model for the PIRRT cohort, the APACHE II score emerged as the most relevant predictor. Each one-point increase in APACHE II was associated with a 23.2% increase in the odds of 7-day mortality (OR: 1.232; p = 0.039), highlighting its clinical relevance in stratifying risk within this population.