Transcultural and Measurement Evaluation of the Asthma Quality-of-Life Questionnaire

ObjectiveThis analysis compared Asthma Quality-of-Life Questionnaire (AQLQ) data from across 16 countries (17 languages) to evaluate suitability to combine data in analyses.Study DesignAQLQ data from the Gaining Optimal Asthma Control study was used for the analyses; 1832 patients had an overall AQLQ score at baseline and week 12. The original North American English version, for Canadian patients only, was the reference language (RL). AQLQ scores range from 1-7, where a high score indicates no impairment. Values within 0.5 of the RL were considered comparable.ResultsThe number of patients varied from 27 (Canadian French) to 257 (Mandarin Chinese). Mean age ranged from 27.6 (Spain Spanish) to 52.9 years (Norway Norwegian). Mean overall AQLQ score (SD) at baseline in the RL was 4.59 (0.94). All but 3 languages reported scores within 0.5 of the RL. Mean change from baseline in the overall AQLQ score in the RL was 0.89 (1.06). Baseline overall AQLQ scores were all within 0.5 of the RL. Cronbach alpha ranged from 0.93 to 0.97 (RL 0.94). Correlation with baseline Asthma Control Questionnaire (ACQ) and the forced expiratory volume in 1 second (FEV1) ranged from −0.76 to −0.58 (RL −0.69) and −0.02 to 0.41 (RL 0.08), respectively. Similarly, correlations with change from baseline for ACQ and FEV1 ranged from −0.83 to −0.61 (RL −0.77) and −0.11 to 0.56 (RL 0.03). Effect sizes were all >0.50, ranging from 0.59 (Norway Norwegian) to 1.10 (New Zealand English) (RL 0.85).ConclusionsThe finding that internal consistency, construct validity, and responsiveness were demonstrated across languages and similar to the RL supports the combining of data for analyses.