Creatinine Paradox in Continuous Renal Replacement Therapy: Higher Levels, Lower Mortality - A Medical Information...

The relationship between baseline serum creatinine (SCr) levels at the initiation of continuous renal replacement therapy (CRRT) and in-hospital mortality remains unclear. This study aimed to investigate this relationship in critically ill patients with acute kidney injury (AKI) undergoing CRRT.

In this retrospective cohort study, data from the Medical Information Mart for Intensive Care IV (MIMIC-IV 2.2) database were categorized into four quartiles based on SCr levels at CRRT initiation, with in-hospital mortality as the primary outcome. We applied Kaplan-Meier curves for outcome comparison across groups. Multivariate Cox pro-portional-hazards models and restricted cubic splines (RCS) were conducted to examine the association between initial SCr and mortality. Additional interaction and subgroup analyses were conducted to reinforce our findings.

In a cohort of 989 AKI patients undergoing CRRT, the mean age was 62.5 years, with 60% being male and an in-hospital mortality rate of 47.5%. Kaplan-Meier curve analysis revealed that higher SCr levels were linked to a lower risk of in-hospital mortality. Cox proportional hazards regression confirmed a significant increase in mortality risk among patients in the lowest SCr quartile. Furthermore, RCS analysis demonstrated an L-shaped relationship between SCr and in-hospital mortality, with an inflection point at 5.75 mg/dL. No interactions were found between SCr and in-hospital mortality.

In critically ill AKI patients requiring CRRT, a paradoxical L-shaped relationship between SCr levels and in-hospital mortality risk was observed, with an inflection point at 5.75 mg/dL. Further large, diverse studies are needed to confirm these results.