EVALUATION OF PEAK EXPIRATORY FLOW VARIABILITY IN AN ADOLESCENT POPULATION-SAMPLE - THE ODENSE SCHOOLCHILD STUDY

The validity of peak expiratory flow (PEF) recordings and the sensitiv ity of PEF variability indices in asthma and asthma-like conditions we re examined in an adolescent population. Recordings from 245 randomly selected subjects and from an additional 181 subjects reporting or con sidered at risk for developing asthma were analyzed. Subjects recorded PEF twice daily for 2 wk using Mini-Wright meters, completed a sympto ms questionnaire, and were tested for airway responsiveness to methach oline. The first three recording days showed significant accumulation of lowest PEF values recorded (41%) and were excluded from further ana lysis. Among nine PEF variability indices, the Two-lowest%mean (the me an of the two lowest PEF values as a percentage of the period mean) ha d the best sensitivity for physician-diagnosed asthma (28%). The sensi tivity of the methacholine dose-response slope (DRS) was 69%. Combinin g these indices, a sensitivity of 77% for diagnosed asthma was obtaine d. Among subjects with asthma-like symptoms but no diagnosis of asthma , 14% had increased Two-lowest%mean and the DRS was increased in 17%, but only 3% were identified by both tests. In conclusion, inhomogeneit y of PEF data could be corrected by disregarding the fi rst three reco rding days. PEF variability indices identified some diagnosed asthmati cs, and particularly some symptomatic ''nonasthmatics'' not identified by the DRS, suggesting that the combined use of these indices might b e helpful.