Hematological and biochemical biomarkers of mortality prognosis in children under five with severe malaria at the Zinder National Hospital, Niger Republic: case–control study

Severe malaria remains a major cause of mortality in children under five in sub-Saharan Africa, particularly in Niger. Early identification of prognostic biomarkers is crucial to reduce deaths. This study aimed to determine the hematological and biochemical biomarkers predictor of mortality in children under five with severe malaria at the Zinder National Hospital, Niger. A matched case–control study (1:2) was conducted among children aged 0–59 months hospitalized for severe malaria during high transmission periods (July to September 2024 and July to September 2025). A total of 64 cases (children who died from severe malaria) and 128 controls (survivors), individually matched 1:2 by age, sex, and hospitalization period, were included. Hematological parameters (complete blood count) and biochemical markers (glucose, urea, and creatinine) were collected from laboratory records. Because a paired Student’s t test is not valid for a 1:2 matched design, univariate and multivariate conditional logistic regression, stratified by matched set, was used to calculate adjusted odds ratios; discriminative performance was assessed by ROC curve analysis, using R software (version 4.5.2). Median hemoglobin was 7.25 g/dL (IQR 4.80–9.65) in controls and 7.00 g/dL (IQR 4.80–9.22) in cases; median leukocyte count was 12.30 × 10 9 /L (IQR 9.28–19.38) in controls and 14.35 × 10 9 /L (IQR 8.82–20.20) in cases. Using conditional logistic regression to account for the 1:2 matched design, blood urea was the only parameter independently associated with mortality in the biochemical model (aOR = 1.15, 95% CI 1.03–1.28, p = 0.011); hemoglobin, platelet count, leukocytes, blood glucose, and creatinine were not independently associated with mortality. The biochemical model showed modest discriminative performance (AUC = 0.644). Elevated blood urea level was independently associated with mortality in children under five with severe malaria at Zinder National Hospital. This marker likely reflects severe metabolic stress and circulatory dysfunction beyond renal impairment alone. Routine urea measurement at admission could improve risk stratification and clinical management. Larger multicenter studies are needed to validate these findings.