RAR and infant mortality: a crucial link in cardiac surgery outcomes

Background: In-hospital mortality remains a significant concern in infant cardiac surgery, yet precise risk stratification tools are lacking. The prognostic value of the red cell distribution width-to-albumin ratio (RAR)-a composite marker of inflammation and nutritional status-remains unestablished in this population. This study aimed to examine the association between RAR and in-hospital mortality in infants undergoing cardiac surgery. Methods: This work constitutes a retrospective observational cohort analysis. The study population comprised infants admitted to Guangdong Provincial People's Hospital for cardiac surgery from January 2017 through October 2021.The optimal cut-off value for the RAR was determined to be 1.35 fL/(g/L) using the Youden index method. Based on this threshold, all participants were categorized into a high-RAR group and a low-RAR group. The relationship between RAR levels and mortality during hospitalization was then examined through multiple analytical approaches, including logistic regression, subgroup analyses, and modeling with restricted cubic splines (RCS).The predictive performance of the RAR was further evaluated through an analysis of the receiver operating characteristic (ROC) curve. Results: Mortality rates in this surgical cohort increased with higher RAR values. A consistent relationship linking the RAR to mortality was observed regardless of whether this biomarker was incorporated into statistical models as a continuous measure or a categorical parameter. Among 3634 patients, logistic regression analysis indicated that infants with RAR > 1.35 fL/(g/L) had a significantly higher mortality risk compared to those with RAR ≤ 1.35 fL/(g/L) (OR = 2.16, 95% CI 1.01-4.60, p < 0.05). Furthermore, the direction of the association was consistent across subgroups. The predictive performance of the model was good, with an area under the ROC curve of 0.8. Conclusion: A higher RAR-specifically a value above 1.35 fL/(g/L)-was associated with increased mortality risk during hospitalization in infants undergoing cardiac surgery. As an easily measurable blood-based indicator, RAR demonstrates potential value for clinical practice and research applications.