Combining PCT, resistin and NGAL in the Alder Hey ED and Alder Hey PICU cohorts improved the summary AUC more substantially for models predicting “definite bacterial” infections vs. “definite viral” infections [summary AUC of 0.83 (95% CI 0.77–0.89)] compared with “SBI” vs. “non-SBI” [summary AUC of 0.71 (95% CI 0.67–0.74)] (Figure 9). The gene discussed is RETN; the disease is infection.