Outcomes associated with spirometry for pediatric asthma in a managed care organization

BACKGROUND. The National Heart, Lung and Blood Institute asthma guidelines recommend that children with asthma receive spirometry testing "at least every 1 to 2 years to assess the maintenance of airway function." OBJECTIVE. The purpose of this work was to describe: (1) how often children with asthma receive spirometry testing, (2) what factors are associated with receipt of spirometry testing, and (3) the impact of spirometry testing on subsequent emergency department visits for asthma. METHODS. We analyzed all pediatric asthma claims data from a university-based managed care organization for a 3-year period (January 2001 to December 2003). We included all of the continuously enrolled patients with active asthma between 7 and 21 years of age. Our outcomes of interest were the presence of ≥1 claim for spirometry testing (Common Procedural Terminology 94010-6, 94060, 94070, or 94150) and the time to emergency department visit. We used multivariate logistic regression to determine factors associated with receipt of spirometry and survival analyses techniques to assess the association between receipt of spirometry with the likelihood of an emergency department asthma visit in the next year, controlling for patient age, gender, severity of illness, and type of insurance. RESULTS. There were 2688 eligible children of whom 1509 (56%) were male, 324 (12%) had Medicaid insurance, and 624 (24%) had persistent asthma in the initial year. Of the 2688 children, only 612 (23%) had ≥1 claim for spirometry testing during the study period. In all of the multivariate logistic analysis models, increased severity of illness was consistently associated with increased likelihood of receiving spirometry testing. Compared with patients without Medicaid insurance, children with Medicaid insurance were consistently less likely to receive spirometry testing. After adjusting for age, gender, severity, and insurance type, receipt of spirometry did not affect the likelihood of future emergency department asthma use. CONCLUSIONS. Children with Medicaid insurance are less likely to receive spirometry testing. Reasons may be because of access to care, inadequate provider referral for testing, or patient preferences. Objective lung function tests, such as spirometry, are a potentially important component of monitoring chronic disease status. However, it is not clear whether spirometry testing by itself, completed every 1 to 2 years, helps prevent the likelihood of emergency department asthma visits. Compared with guideline recommendations, spirometry is underused; however, additional work is needed to understand how to best integrate such testing to improve asthma outcomes.