Validation of the pulmonary score: an asthma severity score for children.

OBJECTIVES: In the absence of a validated "user-friendly" method of scoring asthma severity, the authors derived the pulmonary score (PS). The purpose of this study was to begin validation trials of the PS by comparing it with the peak expiratory flow rate (PEFR).
METHODS: The study enrolled a convenience sample of children, aged 5-17 years, who came to the emergency department (ED) for treatment of an acute asthma exacerbation. The PEFR (best of three attempts) and the PS were measured before and after the first albuterol treatment by a physician and a nurse from a pool of 45 trained observers. The PS includes respiratory rate, wheezing, and retractions, each rated on a 0-3 scale. Decreasing PS and increasing PEFR indicate clinical improvement. Pre- and post-treatment PEFRs and PSs were compared using paired t-tests to establish construct validity. Correlation of pre- and post-treatment PSs with PEFRs was measured to establish criterion validity.
RESULTS: Forty-six subjects completed the study. Mean percent predicted PEFR improved after treatment by 20.7% (p = 0.0001), and mean PS by 1.5 for nursing-obtained scores (p < 0.0001) and 1.9 for physician-obtained scores (p < 0.0001). Pre- and post-treatment PSs were significantly correlated with PEFRs. Correlations for the nursing-obtained scores were pre-treatment r = -0.57 (p = 0.0003) and post-treatment r = -0.67 (p = 0.0001), and for the physician-obtained scores were pre-treatment r = -0.44 (p = 0.003) and post-treatment r = -0.56 (p = 0.0001). The pre-treatment interrater reliability was 0.62 and the post-treatment was 0.53.
CONCLUSIONS: These data support the construct and criterion validities of the PS as a measure of asthma severity among children in the ED. The PS is a practical substitute to estimate airway obstruction in children who are too young or too sick to obtain PEFRs.