Comparison of the responsiveness of different disease-specific health status measures in patients with asthma.

BACKGROUND Disease-specific health status measures are characterized by higher responsiveness than generic measures and may be preferred in clinical trials. However, comparisons of responsiveness between various disease-specific measures have rarely been performed in asthma studies. STUDY OBJECTIVE We investigated and compared the responsiveness of health status scores in asthmatic patients during treatment using three different disease-specific measures: the Juniper Asthma Quality of Life Questionnaire (AQLQ), the Living with Asthma Questionnaire (LWAQ), and the Airways Questionnaire 20 (AQ20). METHODS We attempted to follow up 170 patients with newly diagnosed asthma over a 6-month period. Patients underwent treatment with inhaled corticosteroids in accordance with the guideline. A health status evaluation using three disease-specific measures, and pulmonary function tests were performed on the initial visit, and at 3 months and 6 months. The effect size and the standardized response mean were used as responsiveness indexes. RESULTS A total of 109 patients completed the 6-month follow-up and were then analyzed. All health status scores and FEV(1) measures improved during the first 3 months (p < 0.001). The total of the AQLQ scores showed high responsiveness indexes ranging from 1.28 to 1.46 between baseline and 3 months, and baseline and 6 months. Spearman correlation coefficients were smaller between the change in FEV(1) and the change in the LWAQ. Although the AQ20 also demonstrated high responsiveness, a ceiling effect was indicated. CONCLUSIONS The AQLQ was the most responsive measure during asthma treatment. The relationship between the change in airflow limitation and the change in the LWAQ was weaker compared to the AQLQ and the AQ20. Although the AQ20 was also responsive and its simplicity is favorable, the ceiling effect should be considered when using it.