Home spirometry and asthma severity in children.

The usefulness of peak expiratory flow monitoring is disputed because of the unreliability of written peak flow diaries. The aim of the present study was to examine the relationship of peak flow and forced expiratory volume in one second (FEV1) variation to other estimates of asthma severity in children, using an electronic home spirometer with automatic data storage. Over a 3-month period, 36 children with mild-to-moderate persistent asthma recorded peak flow and FEV1 electronically twice daily and noted an asthma severity score in a written diary. Bronchial responsiveness was assessed at the beginning and bronchodilator response and asthma-specific quality of life at the end of the study. Variations in peak flow correlated significantly but weakly to bronchial responsiveness and bronchodilator response, but not to the asthma severity score or quality-of-life scores. Within-individual correlations between asthma severity scores and home spirometry indices and between peak flow and FEV1 were highly variable. In conclusion, variations in peak flow and forced expiratory volume in one second, obtained by home spirometry, show poor concordance with other indices of disease activity and with each other. This limits the usefulness of home spirometry in childhood asthma.