Spirometry use in children hospitalized with asthma

Asthma is the most common chronic disorder of childhood and continues to be a leading cause of pediatric hospital admission. The National Asthma Education and Prevention Program (NAEPP) recommends that spirometry be obtained for asthma patients upon hospital admission, after bronchodilation during the acute phase of asthma symptoms, and at least one additional time before discharge from the hospital. The objectives of this study were to describe the use of spirometry in children hospitalized with asthma and to determine association of pulmonary function with future exacerbations. A retrospective cohort study design was utilized involving review of medical records of children ≥5 years old admitted with asthma to Cincinnati Children's Hospital Medical Center from September 1, 2009 to March 31, 2011. Hospitalization or emergency department (ED) visits were identified by the ICD-9-CM codes of having either a primary diagnosis of asthma (493) or a respiratory illness (460-496) plus a secondary diagnosis of asthma. Asthma re-exacerbation was defined as either having an ED visit or hospitalization for asthma that occurred within 3 months after the index hospitalization. All spirometries were performed in a pediatric pulmonary function laboratory. Among 1,037 admissions included in this study, 89 (8.6%) had spirometry that was recommended by a consulting asthma specialist and usually performed on the day of discharge. Spirometries for forty-five of these patients (54.9%) met all acceptability and repeatability criteria of the American Thoracic Society. Patients who performed acceptable spirometry were significantly older (12.4 ± 3.8 vs. 10.7 ± 3.0 years; P = 0.041). The average forced expiratory volume in the first second (FEV1 ) was 84.4 ± 19.7% predicted; forced vital capacity (FVC) was 98.1 ± 16.0% predicted; FEV1 /FVC was 74.6 ± 9.6%; forced expiratory flow at 25-75% (FEF25-75 ) was 61.2 ± 30.1% predicted. Ten patients (22%) who performed spirometry developed a re-exacerbation. Patients with versus without re-exacerbation had significantly lower FEV1 /FVC (P = 0.027) and FEF25-75 (P = 0.031). Nevertheless, separate logistic regression models found that FEV1 /FVC and FEF25-75 were not associated with re-exacerbation when adjusted for age and length-of-stay. We found that few children admitted with asthma had spirometry as recommended in the NAEPP guidelines unless recommended by specialists and both lower lung function (FEV1 /FVC and FEF25-75 ) and history of more frequent and more recent prior health-care utilization for asthma were associated with repeat asthma exacerbation. However, the value of performing spirometry on asthmatic children prior to hospital discharge remains unclear and will require prospective study.