To examine the concordance between spirometry and asthma symptoms in assessing asthma severity and beginning therapy by the general pediatrician.

Between 2008 and 2012, spirometry testing was satisfactorily performed in 894 children (ages 5-19 years) whose asthma severity had been determined by their pediatrician using asthma guideline-based clinical criteria. Spirometry-determined asthma severity using national asthma guidelines and clinician-determined asthma severity were compared for concordance using weighted Kappa coefficients.

Thirty percent of participants had clinically determined intermittent asthma; 32%, 33%, and 5% had mild, moderate, and severe, persistent asthma, respectively. Increasing disease severity was associated with decreases in the forced expiratory volume in 1 second/forced vital capacity (FVC) ratio (P < .001), the forced expiratory volume in 1 second/FVC% predicted (P < .0001), and the FVC% predicted (P < .01). In 319 children (36%), clinically determined asthma severity was lower than spirometry-determined severity. Concordance was 0.16 (95% CI 0.10, 0.23), and when adjusted for bias and prevalence, was 0.20 (95% CI 0.17, 0.23). When accounting for age, sex, exposure to smoke, and insurance type, only spirometry-determined asthma severity was a significant predictor of agreement (P < .0001), with worse agreement as spirometry-determined severity increased.

Concordance between spirometry and asthma symptoms in determining asthma severity is low even when guideline-based clinical assessment tools are used. Because appropriate therapy reduces asthma morbidity and is guided by disease severity, results from spirometry testing could better guide pediatricians in determining appropriate therapy for their patients with asthma.