Clinical Citations: Evaluating the reliability of the Asthma Control Test

August 1, 2006

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.

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.