Spirometry, bronchodilator test or symptom scoring for the assessment of childhood asthma

The value of spirometry, the bronchodilator test and 2 weeks' symptom scoring for the assessment of the severity of childhood asthma was studied in a series of 65 consecutively referred school-aged asthmatic children, with the diurnal peak expiratory flow (PEF) variability in home recordings serving as a golden standard. The amplitude of the peak expiratory flow rate (PEFR) variation could be best predicted by the baseline forced expiratory volume in 1 s (FEV1) and the past history of the symptom rate, the correlation with FEV1 being -0.48, p < 0.001. Although the baseline forced expiratory flow between 25 and 75% of the forced vital capacity (FEF25-75%) and the responses of FEV1 and FEF25-75% to salbutamol also showed significant correlations with the diurnal PEFR variability (r = -0.43, r = 0.47 and 0.41, p < 0.001, respectively), these variants did not improve the regression model. The baseline FEV1. FEF25-75% and PEFR and their responses to salbutamol also had a slight but statistically significant correlation with the methacholine threshold, but the symptom score on the diary card did not show comparable correlations with either the diurnal PEFR variability or the methacholine threshold (r = 0.09, NS, and r = 0.05, NS, respectively). These results indicate that both baseline lung function and the response to the bronchodilator test correlate with the severity of childhood asthma more appropriately than does the symptom score on a diary card. Since many of these correlations were rather weak, however, the assessment of the severity of childhood asthma cannot be reliably based solely on spirometry in all patients.