Association Between the Red Cell Distribution Width-to-Albumin Ratio and Pediatric Community-Acquired Pneumonia

Although the prognostic value of the red cell distribution width-to-albumin ratio (RAR) has been well demonstrated in adult diseases, there is a lack of data regarding its role in pediatric community-acquired pneumonia (CAP). We aimed to investigate the association between RAR and pediatric CAP and to evaluate its ability to predict clinical outcomes using routinely available laboratory parameters.

We retrospectively included 1151 children hospitalized with pneumonia between 2013 and 2024. RAR-CV was calculated by dividing red cell distribution width-coefficient of variation (RDW-CV) by albumin concentration, and RAR-SD by dividing red cell distribution width-standard deviation (RDW-SD) by albumin.

RAR values were significantly associated with all outcomes. The area under the curve (AUC) values of RAR for predicting pediatric intensive care unit (PICU) admission, invasive mechanical ventilation (IMV), and vasopressor use were higher than those of its individual components (RDW and albumin). In ROC analyses including all clinical parameters, no variable outperformed RAR in predicting these outcomes. RAR significantly predicted PICU admission, IMV, vasopressor use, and mortality (p < 0.001), and RAR-SD showed good predictive performance for mortality (AUC = 0.809).

To our knowledge, this is the first study to evaluate the prognostic value of RAR in pediatric CAP. Our findings demonstrate a strong association between RAR levels and adverse clinical outcomes. Given its simplicity, cost, and availability, RAR may serve as a valuable biomarker to support risk stratification and prognostication in children with CAP.