Is home spirometry useful in diagnosing asthma in children with nonspecific respiratory symptoms?

Background Variation of lung function is considered to be a hallmark of asthma. Although guidelines recommend measuring it as a diagnostic tool for asthma, the usefulness of this approach has not been studied in children. Aim To assess the usefulness of home spirometry in children with nonspecific lower respiratory tract symptoms, to diagnose or exclude asthma. Methods In school‐aged children, referred by their general practitioner because of chronic respiratory symptoms of unknown origin, the diagnosis of asthma was made or excluded by a pediatric pulmonologist (gold standard), based on international guidelines and a standardized protocol. Additionally, children measured peak expiratory flow (PEF) and forced expiratory flow in 1 sec (FEV1) twice daily for 2 weeks on a home spirometer, from which diurnal variation was calculated. These results (index test) were not revealed to the pediatric pulmonologist. The value of home spirometry to diagnose asthma was calculated. Results Sixty‐one children (27 boys) were included (mean age: 10.4 years; range: 6–16 years). Between asthma and no asthma, the mean difference in PEF variation was 4.4% (95% CI: 0.9–7.9; P = 0.016) and in FEV1 variation 4.5% (95% CI: 1.6–7.4; P = 0.003). Sensitivity and specificity, based on the 95th‐centile of the reference values for PEF and FEV1 variation (12.3% and 11.8%, respectively) were 50% and 72% for PEF variation and 45% and 92% for FEV1 variation. The likelihood ratio was 1.8 for PEF and 5.6 for FEV1. Conclusions The contribution of home spirometry in the diagnostic process for asthma in schoolchildren with nonspecific respiratory symptoms is limited. Pediatr Pulmonol. 2010; 45:326–332. © 2010 Wiley‐Liss, Inc.