C.A. Sorkness

Development of the asthma control test (ACT)

Abstract Background Asthma guidelines indicate that the goal of treatment should be optimum asthma control. In a busy clinic practice with limited time and resources, there is need for a simple method for assessing asthma control with or without lung function testing. Objectives The objective of this article was to describe the development of the Asthma Control Test (ACT), a patient-based tool for identifying patients with poorly controlled asthma. Methods A 22-item survey was administered to 471 patients with asthma in the offices of asthma specialists. The specialists rating of asthma control after spirometry was also collected. Stepwise regression methods were used to select a subset of items that showed the greatest discriminant validity in relation to the specialists rating of asthma control. Internal consistency reliability was computed, and discriminant validity tests were conducted for ACT scale scores. The performance of ACT was investigated by using logistic regression methods and receiver operating characteristic analyses. Results Five items were selected from regression analyses. The internal consistency reliability of the 5-item ACT scale was 0.84. ACT scale scores discriminated between groups of patients differing in the specialists rating of asthma control (F = 34.5, P P 1 (F = 4.3, P = .0052). As a screening tool, the overall agreement between ACT and the specialists rating ranged from 71% to 78% depending on the cut points used, and the area under the receiver operating characteristic curve was 0.77. Conclusion Results reinforce the usefulness of a brief, easy to administer, patient-based index of asthma control.