Further validation and definition of the psychometric properties of the Asthma Impact Survey.

ABSTRACT

BACKGROUND: The Asthma Impact Survey (AIS-6) is a brief disease-specific quality-of-life instrument with limited published validation data. OBJECTIVE: To obtain additional validation data and psychometric properties of the AIS-6. METHODS: In November, 2007, patients with persistent asthma were mailed a survey that included the AIS-6, the mini-Asthma Quality of Life Questionnaire (mAQLQ), and the Asthma Control Test (ACT). Follow-up surveys were sent in April, July, and October 2008. Year 2008 exacerbations and short-acting ß-agonist (SABA) dispensings were captured from administrative data. RESULTS: A total of 2680 patients had complete baseline survey data. Criterion validity was demonstrated by the strong correlations of the AIS-6 with the mAQLQ (r = -0.84 to -0.86); construct validity by significant relationships (P < .0001) of the AIS-6 with mAQLQ domain scores, ACT score, and history of exacerbations; and predictive validity by significant relationships (P < .0001) between AIS-6 scores at the end of 2007 and year 2008 exacerbations and high SABA dispensings. Responsiveness was demonstrated by significant (P < .0001) correlations (r = -0.39 to -0.58) between changes in AIS-6 scores and changes in mAQLQ and ACT scores over time. A preliminary minimally important difference (MID) in AIS-6 was estimated to be 4 by using the mAQLQ MID as an anchor. Excellent internal consistency (α = 0.94) and test-retest reliability (intraclass correlation coefficient = 0.86-0.91) were also demonstrated. CONCLUSION: The AIS-6 demonstrated good psychometric properties in a large independent sample and could be used to assess asthma-specific quality of life in clinical practice and clinical research.