Purpose of the Study. Objective measurements of pulmonary function are advised as part of the chronic assessment of children with asthma, because both patients and physicians are imperfect at assessing the degree of airway obstruction without such measurements. Furthermore, it is thought that these measures might predict important disease outcomes, such as exacerbations, disease progression, and functional impairment. These investigators examined the relationship between forced expiratory volume in 1 second (FEV1) and subsequent asthma outcomes, specifically asthma attacks, during a longitudinal study of pediatric lung health.
Study Population. A retrospective cohort analysis of 13 842 subjects seen annually was analyzed for pulmonary function and answers to a respiratory questionnaire. The study entries consisted of all first and second graders from both the private and public schools in communities of 6 states in America.
Methods. Children were followed for up to 15 years. The annual questionnaire requested information as to any known diagnosis of asthma and any attacks of wheezing and shortness of breath within the past year. Questionnaires were answered by parents until children reached approximately age 14 years. The older children usually filled out their own questionnaires.
Results. Of the original study population, 3626 children, comprising a total of 31 075 observations, reported an asthma attack at some time during follow-up. The analysis was restricted to the 95% of these children for whom questionnaire data could be paired with FEV1 values 1 year earlier. Most had at least 7 observations. Predicted FEV1 (FEV1%) was categorized with 2 different schemes (<60%, 60%–80%, and >80%; also, <80%, 80%–100%, and >100%) for multivariate models. An asthma attack was reported at 27% of the observations. Both analyses showed that the risk of asthma attack increased as FEV1% category decreased. Among the parental report group the odds ratios were 2.1 and 1.4 and in the self-report group 5.3 and 1.4 for FEV1% <60% and FEV1% 60%–80% respectively, when compared to FEV1 >80% for each reporting group.
Conclusions. The strong association between FEV1% and risk of subsequent asthma attacks reinforces the importance of routine measurement of pulmonary function in the ongoing management of children with asthma. Because many downstream consequences of asthma are the direct result of airway obstruction, it makes sense to use a test that accurately and reproducibly measures baseline obstruction.
Reviewer’s Comments. No single parameter in history, physical examination, pulmonary function measurement, and therapy suffices to predict future adverse asthma outcomes, but FEV1% belongs on a short list of important data to monitor. The authors point out that various clinical trials suggest that improvements in FEV1 parallel improvements in other asthma outcomes such as exacerbations, health care utilization, symptoms, health-related quality of life, and rescue medication use. Any child on asthma controller therapy should have spirometry performed at least annually, but this is seldom done in primary care in the United States. One explanation for better asthma outcomes in the hands of allergists and pulmonologists likely relates to the routine incorporation of FEV1 data in the overall clinical assessment.
- Copyright © 2002 by the American Academy of Pediatrics