Respiratory Severity Score Separates Upper Versus Lower Respiratory Tract Infections and Predicts Measures of Disease Severity

Background: A respiratory severity score (RSS) describing acute respiratory illness (ARI) severity would be useful for research and clinical purposes. Methods: A total of 630 term infants presenting with ARI had their RSS measured. Results: RSS was higher in those with lower respiratory tract infection (LRTI) compared with those with upper respiratory infection (URI; LRTI 6.5 [4–8.5]; URI 1 [0–2], p <0.001) and in hospitalized infants compared with outpatients (hospitalized 6.5 [4–9]; outpatient 1 [0–3], p <0.001). Conclusions: RSS is higher in LRTI compared with URI and in hospitalized compared with nonhospitalized infants.