Validation of a standardized version of the Asthma Quality of Life Questionnaire

Background: In the original 32-item Asthma Quality of Life Questionnaire (A QLQ), five activity questions are selected by patients themselves. However, for long-term studies and large clinical trials, generic activities may be more appropriate. Methods: For the standardized version of the AQLQ, the AQLQ(S), we formulat ed five genetic activities (strenuous exercise, moderate exercise, work-rel ated activities, social activities, and sleep) to replace the five patient- specific activities in the AQLQ. In a 9-week observational study, nle compa red the AQLQ with the AQLQ(S) and examined their measurement properties. Fo rty symptomatic adult asthma patients completed the AQLQ(S), the AQLQ, the Medical Outcomes Survey. Short Form 36, the Asthma Control Questionnaire, a nd spirometry at baseline, 1, 5, and 9 weeks. Results: Activity domain scores (mean +/- SD) were lower with the AQLQ (5.7 +/- 0.9) than with the AQLQ(S) (5.9 +/- 0.8; p = 0.0003) and correlation b etween the two was moderate (r = 0.77), However, for overall scores, there was minimal difference (AQLQ, 5.4 +/- 0.8; AQLQ(S), 5.5 +/- 0.8; r = 0.99), Reliability (AQLQ intraclass correlation coefficient, 0.99; AQLQ(S) intrac lass correlation coefficient, 0.96) and responsiveness (AQLQ, p < 0.0001; A QLQ(S), p < 0.0001) were similar for the two instruments. Construct validit y (correlation with other measures of health status and clinical asthma) wa s also similar for the two instruments. Conclusions: The AQLQ(S) has strong measurement properties and is valid for measuring health-related quality of Life in asthma, The choice of instrume nt should depend on the task at hand.