Psychometric performance of the Asthma Quality of Life Questionnaire in a US sample.

The purpose of this study was to examine the psychometric characteristics of the Juniper Asthma Quality of Life Questionnaire (AQLQ) in a sample of asthmatics from the USA, employing data from the Asthma Symptom Utility Index (ASUI) validation study. One hundred and sixty-one adults (66 men) undergoing standard care in an asthma clinic participated in the study (mean age = 34.7 +/- 10.7 years, mean duration of illness = 17.3 +/- 11.22 years and mean FEV1% predicted = 85.6% +/- 17.1%). The internal consistency reliability (infinity) ranged from 0.90 (environment subscale) to 0.95 (overall score) and the 2 week reproducibility (ICC) ranged from 0.81 (activities subscale) to 0.93 (symptoms subscale). The AQLQ was significantly correlated with an asthma disease severity scale and the Health Utilities Index (p < 0.001). No relationship was found between the AQLQ score and FEV1% predicted. Men reported better overall quality of life (QoL), fewer activity limitations and less environmental exposure than women (p < 0.01), while patients with a high school education or less had more severe asthma and poorer QoL across all subscales (p < 0.001). This may reflect the differential experiences of asthma across gender and socioeconomic groups. The results suggest that the AQLQ may be a useful outcome measure for clinical trials conducted in the USA.