Objective: To evaluate the discriminative properties and validity of the Airways Questionnaire 20 (AQ20) in a sample of patients with airway obstruction and to compare its properties with those of the St George's Respiratory Questionnaire (SGRQ) and the Short Form 36 (SF-36).
Patients and methods: A convenience sample of 47 subjects was recruited from among 61 consecutive patients referred to an outpatient clinic specialized in obstructive airway diseases. All subjects completed the AQ20, SGRQ, and SF-36. Other measures were the baseline dyspnea index (BDI), 6-minute walk test (6MWT) distance, spirometry, results of arterial blood gas analysis, and body mass index.
Results: The AQ20 showed very good correlation with the SGRQ total score (rho=0.84, P< .001) and moderate correlation with all SF-36 domains (physical capacity, rho=-0.53; physical functioning, rho=-0.61; bodily pain, rho=-0.55; general health, rho=-0.59; vitality, rho=-0.55; social functioning, rho=-0.57; emotional role functioning, rho=-0.51; mental health, rho=-0.61; all P< .001). The BDI and the 6MWT distance were the best predictors of AQ20 score (r2=0.31) in the regression model. An area under the receiver operating characteristic curve of 0.91 (P< .001) indicated a high level of accuracy for the AQ20, using the SGRQ as the gold standard.
Conclusion: This study shows that the AQ20 is an accurate health status questionnaire in patients with moderate-to-severe airway obstruction. It could be an alternative to longer, traditional questionnaires such as the SGRQ.