Assessing meaningful change in the Asthma Impairment and Risk Questionnaire

Background: The Asthma Impairment and Risk Questionnaire (AIRQ) is a 10-item, yes/no, equally weighted control tool. Lower scores indicate better control. Moreover, 7 impairment items reflect previous 2-week symptoms, and 3 risk items assess previous 12-month exacerbations. The Follow-up AIRQ for use between annual assessments has a 3-month recall period for exacerbation items.

Objective: To evaluate the responsiveness of the AIRQ over time and identify a minimal important difference (MID).

Methods: The AIRQ longitudinal study data were analyzed from patients with asthma aged 12 years and older. Anchor-based methods assessed differences in AIRQ scores relative to Patient Global Impression of Change, the accepted MIDs for St. George's Respiratory Questionnaire and Asthma Control Test, and exacerbation occurrence over 12 months. Baseline and 12-month data reflected 12-month recall AIRQ scores; Follow-up AIRQ scores were used for 3-, 6-, and 9-month analyses.

Results: A total of 1070 patients were included. The Patient Global Impression of Change rating of "much improved" was associated with AIRQ mean score changes from baseline to months 3, 6, 9, and 12 of -2.0, -1.9, -1.9, and -1.8, respectively. The mean AIRQ score change among patients who met the St. George's Respiratory Questionnaire MID (≥4-point decrease) was -1.8 at 6 and 12 months. The AIRQ mean scores decreased from baseline by -2.2 to -2.5 points at months 3, 6, 9, and 12 for patients who met the Asthma Control Test MID (≥ 3-point increase). A 2-point higher baseline AIRQ score was associated with a 1.7 odds ratio of 12-month exacerbation occurrence (95% CI, 1.53-1.89).

Conclusion: A change score of 2 is recommended as the AIRQ MID.