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

Abstract

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.

FIG. 1.

Respiratory severity scale (RSS) separates individual infants with lower respiratory tract infection (LRTI; red dots) from those with upper respiratory tract infection (URI; blue dots) (A), and separates infants who required inpatient care (red dots) from those managed as outpatients (blue dots) (B). (C) and (D) Separate multivariable logistic regressions were used to assess the relationship of RSS with URI diagnosis (C) and RSS with inpatient care (D), adjusting for infant age at time of acute respiratory illness (ARI), sex, birth weight, gestational age, insurance status, presence of siblings, maternal tobacco current use, and race. The RSS was included as a flexible smooth parameter using splines. The predicted probability of LRTI versus URI diagnosis (C) or of inpatient versus outpatient care (D) increases as RSS increases.