The Asthma Quality of Life Questionnaire (AQLQ) was developed to measure the functional problems (physical, emotional, social and occupational) that are most troublesome to adults (17-70 years) with asthma.
After identifying all the possible problems that adults with asthma may experience, we asked 150 patients to tell us which of these problems they had experienced as a result of their asthma. They were then asked to score the importance of each of the positively identified problems (0= not important - 4 = very important). The items that were identified most frequently and scored highest were included in the AQLQ. The highest scoring problems were the same for both men and women, for patients with a wide range of asthma severity (no medication to oral steroids) and in different age groups. Therefore, the AQLQ is suitable for all adult patients with asthma. Subsequent cultural adaptation studies have also shown that the same problems are troublesome to asthma patients worldwide.
There are 32 questions in the AQLQ and they are in 4 domains (symptoms, activity limitation, emotional function and environmental stimuli). The activity domain contains 5 ‘patient-specific’ questions. This allows patients to select 5 activities in which they are most limited and these activities will be assessed at each follow-up. Patients are asked to think about how they have been during the previous two weeks and to respond to each of the 32 questions on a 7-point scale (7 = not impaired at all - 1 = severely impaired). The overall AQLQ score is the mean of all 32 responses and the individual domain scores are the means of the items in those domains.
In more than 6 published validation studies conducted in a variety of countries, the AQLQ has shown very strong measurement properties. It has excellent test-retest reliability (intraclass correlation coefficient > 0.95) and is easily able to discriminate between patients of different levels of impairment. The AQLQ is also very responsive to within-patient change over time. This is the property that is needed both in clinical practice and in clinical trials where it is important to be able to detect small changes within individual patients even if the changes are small. Extensive construct validity studies (both cross-sectional and longitudinal) have shown that the AQLQ correlates appropriately with other measures of clinical asthma status and generic health status and responds to known efficacious treatment. These studies have built up very strong evidence that the AQLQ really does measure the health-related quality of life of adults with asthma. In addition, we have shown that a change in score of 0.5 on the 7-point scale is the smallest change that can be considered clinically important and would justify a change in the patient’s treatment (in the absence of undue side effects or excessive costs). This is known as the Minimal Important Difference (MID).
Original language: English for North America
Formats: Paper: Interviewer-administered and self-administered