Predicting episodes of poor asthma control in treated patients with asthma

Background

Asthma exacerbations are dangerous, expensive, and difficult to anticipate.

Objective

To characterize patients with asthma who had asthma episodes and exacerbations during 4 weeks of observation.

Methods

A total of 2032 volunteers with asthma (age, 3-64 years; 62% female subjects) were studied over two 2-week intervals after flu vaccine and placebo. Baseline data, including several asthma questionnaires, were analyzed for prediction of subsequent asthma events as recorded on diaries detailing peak flow, medication use, and health care use.

Results

During 28 days of diary collection, 43.2% of participants had at least 1 episode of poor asthma control. Most episodes were characterized by increased use of rescue medications or reductions in peak flow, but nearly 15% of participants had exacerbations characterized by use of systemic corticosteroids, unscheduled health care visits, or both. Episode frequency was highest in children <10 years of age. Additional risk factors were smoking, African American ethnicity, low lung function, and past history of severe asthma. The best predictors were symptom questionnaires, and a simple questionnaire concerning the preceding 2 weeks worked as well as more complex questionnaires or those reflecting longer periods. In regression analyses, questionnaire results, smoking, lung function, ethnicity, and asthma history all were associated with asthma episodes in people older than 10 years, whereas only asthma history was predictive in those <10 years.

Conclusion

Symptom questionnaires are predictive of subsequent asthma episodes in people older than age 10 years, but not in younger people.

Clinical implications

Simple assessments may be helpful in identifying patients most at risk for future asthma episodes.

Key words: Asthma exacerbations, asthma symptom questionnaires, asthma control

Abbreviations used: AS-2, Two-week Asthma Symptom score, AS-52, Fifty-two–week Asthma Symptom score, ASUI, Asthma Symptom Utility Index, BMI, Body mass index, EPAC, Episode of poor asthma control, GINA, Global Initiative for Asthma, GINAMED, Global Initiative for Asthma medication group, ICS, Inhaled corticosteroid, IRA, Increased Risk Assessment, OCS, Oral corticosteroid, RR, Relative risk