The non-linear association between creatinine-to-albumin ratio and medium-term mortality in patients with sepsis accompanied by acute kidney injury in the intensive care unit: a retrospective study based on the MIMIC database and external validation

CAR is an independent predictor of 30-day mortality in sepsis-associated AKI, with both continuous measurements and the highest quartile (Q4) demonstrating significant associations after comprehensive adjustment for metabolic and hemodynamic parameters. The identified threshold (CAR = 1.2 mg/dL) enhances its clinical utility. While CAR provides independent prognostic information, its modest effect sizes suggest it should be used as a complementary tool rather than a standalone predictor. CAR's simplicity and accessibility make it a valuable adjunct for risk stratification in this high-risk population.