Clinical Citations: Evaluating the reliability of the Asthma Control Test

Effective asthma control involves the assessment of symptoms, changes in pulmonary function, and effects on quality of life and functional ability. A 5-item, patient-administered survey, the Asthma Control Test (ACT), has been developed as an assessment tool (Table). Investigators evaluated the reliability and validity of the ACT in a longitudinal study of patients with asthma who were new to the care of an asthma specialist.

At 2 physician office visits scheduled 4 to 12 weeks apart, 313 patients completed the ACT; a previously validated tool to measure asthma control, the Asthma Control Questionnaire (ACQ); and prebronchodilator measurements of forced expiratory volume in 1 second (FEV₁).

Results of the survey evaluation showed internal consistency reliability of 0.85 at the baseline visit and 0.79 at the follow-up visit, and test-retest reliability was 0.77. Results also demonstrated the following: criterion validity, with significant correlations between baseline ACT scores and baseline specialists' ratings of asthma control; discriminant validity, with significant differences in mean ACT scores across patients differing in pulmonary function, asthma control, and treatment recommendation; and responsiveness, with significant correlations between changes in ACT scores and changes in specialists' ratings, ACQ scores, and percent of predicted FEV₁ values.

The authors concluded that the ACT is reliable, valid, and responsive to changes in asthma control over time in patients who are new to the care of asthma specialists.