Comparison of health-related quality of life measures in asthma-COPD overlap

OBJECTIVE: The Asthma Quality of Life Questionnaire (AQLQ) and COPD assessment test (CAT) are used to assess the health status of asthma and chronic obstructive pulmonary disease (COPD), respectively. However, whether these questionnaires are appropriate in patients with asthma-COPD overlap (ACO) has not been reported. This study aimed to evaluate the performance of the AQLQ and CAT in subjects with ACO. METHODS: Subjects were enrolled from two previously described observational studies in Beijing, China. ACO was defined by a consensus definition from a roundtable discussion. All subjects completed the AQLQ, CAT, St George’s Respiratory Questionnaire (SGRQ), pulmonary function tests, and the Asthma Control Questionnaire (ACQ)-5. Cross-sectional construct validity was evaluated by correlating the AQLQ and CAT with SGRQ score and other measures of asthma and COPD severity. RESULTS: 147 subjects with ACO were recruited. There were floor effects on non-respiratory components of the CAT, and ceiling effects on emotion domains of the AQLQ. Both questionnaires were significantly correlated with ACQ-5 score but were not correlated with FEV(1)% predicted or FVC% predicted. The AQLQ and CAT were strongly correlated with SGRQ score (r = −0.657 and r = 0.623, respectively). Multivariable linear regression analysis showed that the AQLQ (standardized β-coefficient = −0.449, p < .001) had a stronger association with SGRQ score compared with CAT (standardized β-coefficient = 0.211, p = .023). DISCUSSION: The AQLQ and CAT were both valid for assessing the health-related quality of life in subjects with ACO, but the AQLQ performed better than CAT.