Peak flow variation in childhood asthma: correlation with symptoms, airways obstruction, and hyperresponsiveness during long term treatment with inhaled corticosteroids

摘要

BACKGROUND—Guidelinesfor asthma management focus on treatment with inhaled corticosteroidsand on home recording of peak expiratory flow (PEF). The effect ofmaintenance treatment with inhaled corticosteroids on PEF variation andits relation to other parameters of disease activity were examined in102 asthmatic children aged 7-14 years.
METHODS—During 20 months of treatment with inhaled salbutamol, with or without inhaledbudesonide (600 µg daily), forced expiratory volume in one second(FEV1), the dose of histamine required to provoke a fall inFEV1 of more than 20% (PD20), the percentage of symptom free days, and PEF variation were assessed bimonthly. PEFvariation was computed as the lowest PEF as a percentage of the highestPEF occurring over 14 days, the usual way of expressing PEF variationin asthma self-management plans. For each patient using inhaledcorticosteroids within subject correlation coefficients (ρ) werecomputed of PEF variation to the percentage of symptom free days,FEV1, and PD20.
RESULTS—PEF variationdecreased significantly during the first two months of treatment withinhaled corticosteroids and then remained stable. The same pattern wasobserved for symptoms and FEV1. In contrast,PD20 histamine continued to improve throughout the whole follow up period. In individual patients predominantly positive associations of PEF variation with symptoms, FEV1, andPD20 were found, but the ranges of these associations were wide.
CONCLUSIONS—Duringtreatment with inhaled corticosteroids the changes in PEF variationover time show poor concordance with changes in other parameters ofasthma severity. When only PEF is monitored, clinically relevantdeteriorations in symptoms, FEV1, or PD20 maybe missed. This suggests that home recording of PEF alone may not besufficient to monitor asthma severity reliably in children.