Validation of a Spanish version of the airways questionnaire 20: a short and simple instrument

To describe the psychometric properties of the Spanish version of the Airways Questionnaire 20 (AQ20S) for asthma and COPD separately. Two hundred and eight patients (108 asthma, 100 COPD) filled in the AQ20S, the St. George's Respiratory Questionnaire (SGRQ), the Asthma Quality of Life Questionnaire (AQLQ) and the Chronic Respiratory Disease Questionnaire (CRQ). Clinical and physiological measurements were assessed concurrently. Clinically stable patients were asked to fill in again the AQ20S after 14 days. The same assessment as on baseline visit was repeated after 3 months. The AQ20S showed a satisfactory score distribution, with minimal floor and ceiling effects, high internal consistency (Cronbach's alpha > 0.80), and good test-retest reliability (ICC a parts per thousand yen 0.87). The AQ20S showed a high correlation with the SGRQ in both asthma and COPD (r (s) > 0.75; P < 0.001), as well as with the AQLQ (r (s) = -0.72, P < 0.001) in asthma and with the CRQ (r (s) = -0.59; P < 0.001) in COPD. The AQ20S showed significant correlation with clinical and functional variables, similar to the SGRQ and the AQLQ in asthmatics, but weaker than the SGRQ in COPD patients. Changes in AQ20S scores correlated quite well with changes in other HRQoL questionnaires, both in asthma and COPD. The AQ20S showed psychometric properties similar to the original questionnaire. It was equally useful compared with the SGRQ and the AQLQ in asthma patients and slightly less useful than the SGRQ in COPD patients. Considering its simplicity, the AQ20S may be an alternative to more complex traditional questionnaires.