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. (C) 2010 Wiley-Liss, Inc.