Comparison of the psychometric properties of the Asthma Quality of Life Questionnaire (AQLQ) among 115 asthmatic adults assessed during acute hospitalization and as outpatients

Health status instruments designed for outpatient settings may not perform as intended when applied to hospitalized patients. In this study, we assessed similarities and differences between the psychometric properties of the Asthma Quality of Life Questionnaire (AQLQ) in-hospital and during an outpatient visit 6 months later, in a cohort of 115 patients. No ceiling or floor effects were present at either visit. At both visits, all scales except for 'environment' had internal consistency coefficients >0.7 (Environment: 0.69 hospitalization; 0.68 - outpatient). On both occasions, over 75% of item-scale correlation scores were > 0.4 and over 80% correlated to a greater degree with their own scale total than with the other three scales. However, at both visits, the AQLQ standard activity items had a higher correlation with the environment scale than with respondent-defined activity items, this finding re-occurred during exploratory factor analysis. Finally, the AQLQ performed similarly in construct validity tests in the two settings. In conclusion, this study provides evidence that the AQLQ has similar psychometric properties during an acute hospitalization and subsequently in an outpatient setting.