Asthma Control Test Composite Score May Not be Superior to Assessments of Rescue Inhaler Use for Predicting Severe Asthma Exacerbations

Rationale: Current U.S. guidelines recommend the Asthma Control Test (ACT) for assessing disease control and selecting treatment. The ACT was initially validated based on concurrence with specialist opinion. The goal of this study was to prospectively assess the ACT and its component questions for their utility in predicting severe exacerbations.

Methods: Study individuals were participants in the Study of Asthma Phenotypes and Pharmacogenomic Interactions by Race-ethnicity (SAPPHIRE) and had the following characteristics: age ≥18 years, physician diagnosis of asthma, and membership in a health system serving southeastern Michigan.  Participants underwent a baseline evaluation that included the ACT. Severe asthma exacerbations, defined as the need for oral steroids, emergency room visit, or inpatient admission, were identified prospectively using pharmacy claims and patient encounters. Receiver-operator curves were used to assess predictive utility, and the area under the curve (AUC) was used for comparisons.  

Results: Two hundred thirty two (23.4%) of the 990 participants experienced an asthma exacerbation in the 6 months following their baseline evaluation.  The ACT composite score had an AUC of 0.675. With the exception of the rescue inhaler use question, the composite ACT score was significantly better in predicting exacerbations when compared to the 4 other ACT questions. Pharmacy records of concurrent SABA MDI use were equally predictive of exacerbation when compared to the composite ACT score.

Conclusions: Our study demonstrates that while the ACT is predictive for exacerbations, the composite score may not be superior to assessing SABA rescue use alone when predicting risk of serious asthma exacerbations.