Association between red cell distribution width-to-albumin ratio and sepsis-associated acute kidney injury.

BACKGROUND: Sepsis is a critical syndrome frequently observed in the ICU and remains a major worldwide health challenge. Recent data indicate that roughly one fifth of non-critical sepsis patients develop SA-AKI, and its frequency continues to rise. Although the RA has emerged as a novel indicator, its value in forecasting SA-AKI remains poorly characterized. Accordingly, we sought to determine whether RA independently predicts SA-AKI. METHODS: We retrospectively analyzed 133 sepsis patients admitted to our ICU between September 2019 and September 2021. AKI was diagnosed according to KDIGO criteria, and patients were classified into AKI and non-AKI groups based on the occurrence of SA-AKI within 28 days after ICU admission. The predictive value of RA for SA-AKI was assessed using univariate and multivariable logistic regression. Subgroup analyses were stratified by sex, age, APACHE II score, comorbidities, mechanical ventilation, and vasoactive drug use. Discrimination was evaluated using ROC curves; AUCs were calculated and compared using the DeLong method, and optimal cut-off values were determined by the Youden index. RESULTS: Of the 133 included sepsis patients, 56 (42.1%) developed SA-AKI during ICU stay. Intergroup comparisons showed significant differences in RA, procalcitonin (PCT), lactate, RDW, mean platelet volume (MPV), APACHE II score, and the use of mechanical ventilation or vasopressors (all p < 0.05). After multivariable adjustment, RA remained independently associated with SA-AKI (OR 1.53; 95% CI 1.06–2.21; p = 0.023). Subgroup analyses supported the robustness of this association across clinical strata. RA showed modest discrimination for SA-AKI (AUC 0.635, 95% CI 0.540–0.731). The combined model (RA plus creatinine at ICU admission) improved discrimination (AUC 0.715, 95% CI 0.621–0.798; DeLong test p = 0.064). The optimal cut-off values were 0.446 (RA) and 0.356 (combined model) by the Youden index. CONCLUSION: Elevated RA independently predicts SA-AKI, supporting its utility as a readily available early warning marker in septic patients.