CRP-To-Albumin Ratio and CALLY Index for Sepsis Identification and Mortality Discrimination in Critically Ill Children.

backgroundWe compared the diagnostic and prognostic performance of the C-reactive protein-to-albumin (CRP/alb) ratio, neutrophil-to-albumin ratio (NAR), and C-reactive protein-albumin-lymphocyte (CALLY) index in critically ill children.

methodsThis retrospective study included 302 children (1 month-18 years) admitted to a PICU between 2023 and 2025. Outcomes were PICU mortality and sepsis (IPSCC criteria). Discrimination was assessed via ROC analysis; independent associations were evaluated using adjusted logistic regression. Analyses assessed discrimination and adjusted associations rather than a clinical prediction model.

resultsMortality was 19.2%; 43.0% had sepsis. For sepsis identification, the CRP/alb ratio had the highest area under the curve (AUC 0.868) with a higher AUC than the CALLY index (AUC 0.845; p = 0.012) but performed comparably to CRP alone (AUC 0.864; p = 0.217). NAR showed poor discrimination (AUC 0.571). For mortality, CRP/alb (AUC 0.757), CRP (AUC 0.751), and CALLY (AUC 0.743) demonstrated similar discrimination (all p > 0.05). Lower CALLY values independently predicted sepsis (aOR 0.94; 95% CI 0.90-0.98; p = 0.002). The CRP/alb ratio (aOR 1.17 per 10-unit increase; 95% CI 1.06-1.29; p = 0.002) and lactate (aOR 1.34; 95% CI 1.16-1.55; p < 0.001) independently predicted mortality. NRI/IDI analyses showed that composite indices did not improve risk reclassification beyond CRP alone and occasionally worsened it, particularly for sepsis.

conclusionsThe CRP/alb ratio showed higher discrimination for sepsis than the CALLY index and was the only composite index independently associated with mortality. However, reclassification analyses did not support incremental value beyond CRP alone. Composite indices showed comparable rather than additive performance relative to CRP in this population.