PEAK FLOW VARIATION IN CHILDHOOD ASTHMA - RELATIONSHIP TO SYMPTOMS, ATOPY, AIRWAYS OBSTRUCTION AND HYPERRESPONSIVENESS

Although home recording of peak expiratory flow (PEF) is considered us eful in managing asthma, little is known about the relationship of PEF variation to other indicators of disease activity, We examined the re lationship of PEF variation, expressed in various ways, to symptoms, a topy, level of lung function, and airways hyperresponsiveness;ess in s choolchildren with asthma. One hundred and two asthmatic children (age d 7-14 yrs) recorded symptoms and PEF (twice daily) in a diary for 2 w eeks after withdrawal of all anti-inflammatory maintenance medication, PEF variation was expressed as amplitude % mean, as standard deviatio n and coefficient of variation of all recordings, and as low % best (l owest PEF as percentage of the highest of all values). Atopy and level of forced expiratory volume in one second (FEV1) % predicted were not significantly related to PEF variation, The provocative dose of hista mine causing a 20% fall in FEV1 (PD20) and symptom scores were signifi cantly, but weakly, related to PEF variation, The index, low % best, p roved easy to calculate and effective in identifying a short-term epis ode of reduced PEF. We conclude that peak expiratory flow variation in children with stable, moderately severe asthma is significantly, but weakly, related to symptoms and airways hyperresponsiveness, These thr ee phenomena, therefore, all provide different information on the actu al disease state, Expressing peak expiratory flow variation as low % b est is easy to perform and appears to be clinically relevant.