Performance of a novel clinical score, the pediatric asthma severity score (PASS), in the evaluation of acute asthma

Objectives: To evaluate the reliability, validity, and responsiveness of a new clinical asthma score, the Pediatric Asthma Severity Score (PASS), in children aged 1 through 18 years in an acute clinical setting. Methods: This was a prospective cohort study of children treated for acute asthma at two urban pediatric emergency departments (EDs). A total of 852 patients were enrolled at one site and 369 at the second site. Clinical findings were assessed at the start of the ED visit, after one hour of treatment, and at the time of disposition. Peak expiratory flow rate (PEFR) (for patients aged 6 years and older) and pulse oximetry were also measured. Results: Composite scores including three, four, or five clinical findings were evaluated, and the three-item score (wheezing, prolonged expiration, and work of breathing) was selected as the PASS. Interobserver reliability for the PASS was good to excellent (kappa = 0.72 to 0.83). There was a significant correlation between PASS and PEFR (r = 0.27 to 0.37) and pulse oximetry (r = 0.29 to 0.41) at various time points. The PASS was able to discriminate between those patients who did and did not require hospitalization, with area under the receiver operating characteristic curve of 0.82. Finally, the PASS was shown to be responsive, with a 48% relative increase in score from start to end of treatment and an overall effect size of 0.62, indicating a moderate to large effect. Conclusions: This clinical score, the PASS, based on three clinical findings, is a reliable and valid measure of asthma severity in children and shows both discriminative and responsive properties. The PASS may be a useful tool to assess acute asthma severity for clinical and research purposes.