Olavi Linna1. 1. Department of Paediatrics, University of Oulu, Oulu, Finland. olavi.linna@ppshp.fi
Abstract
AIMS: To ascertain whether the severity of childhood asthma can be reliably assessed by simple clinical features, 94 newly diagnosed, school-aged asthmatic children were investigated. METHODS: The study included parental interviews, physical examination, skin prick tests, lung function studies, including a brief visual interpretation of the flow-volume curve, and a 6-min exercise challenge test on a treadmill, which was used as a reference. RESULTS: Baseline lung function studies showed a concave-shaped flow-volume curve in 40 (43%) patients, reduced maximal mid-expiratory flow (MMEF) in 25 (27%) and a reduced ratio of forced expiratory volume in 1 s to forced vital capacity (FEV(1)/FVC) in 14 (15%). The drop in peak expiratory flow (PEF) after exercise ranged from 0 to 79% of the baseline (mean 21.3%) and exceeded 12.5% in 52 (55%) patients. There was a small but significant correlation between the baseline FEV(1)/FVC and MMEF values and the response to exercise (r=-0.39 and -0.35; p=0.000, respectively), but when studied by linear regression analysis, the response to exercise was best predicted by the past symptom rate and a concave pattern in the pre-test maximal expiratory flow-volume curve. The values of traditional lung function tests or age, atopy, duration of symptoms or history of exercise-induced wheezing did not remain in the model. CONCLUSIONS: These results show that the severity of asthma in school-aged children can be predicted at the first visit based on the past rate of symptoms and a visual interpretation of the maximal expiratory flow-volume curve.
AIMS: To ascertain whether the severity of childhood asthma can be reliably assessed by simple clinical features, 94 newly diagnosed, school-aged asthmatic children were investigated. METHODS: The study included parental interviews, physical examination, skin prick tests, lung function studies, including a brief visual interpretation of the flow-volume curve, and a 6-min exercise challenge test on a treadmill, which was used as a reference. RESULTS: Baseline lung function studies showed a concave-shaped flow-volume curve in 40 (43%) patients, reduced maximal mid-expiratory flow (MMEF) in 25 (27%) and a reduced ratio of forced expiratory volume in 1 s to forced vital capacity (FEV(1)/FVC) in 14 (15%). The drop in peak expiratory flow (PEF) after exercise ranged from 0 to 79% of the baseline (mean 21.3%) and exceeded 12.5% in 52 (55%) patients. There was a small but significant correlation between the baseline FEV(1)/FVC and MMEF values and the response to exercise (r=-0.39 and -0.35; p=0.000, respectively), but when studied by linear regression analysis, the response to exercise was best predicted by the past symptom rate and a concave pattern in the pre-test maximal expiratory flow-volume curve. The values of traditional lung function tests or age, atopy, duration of symptoms or history of exercise-induced wheezing did not remain in the model. CONCLUSIONS: These results show that the severity of asthma in school-aged children can be predicted at the first visit based on the past rate of symptoms and a visual interpretation of the maximal expiratory flow-volume curve.