Assessment of impairment in health-related quality of life in patients with difficult asthma: psychometric performance of the Asthma Quality of Life Questionnaire.

OBJECTIVE AND
BACKGROUND: To understand the effects of asthma and its treatment and to draw accurate conclusions with respect to different management programmes, including clinical trials. In more severe asthmatics, it is imperative that the health-related quality of life (HRQL) be measured accurately and validly. This study had a twofold objective: (i) to examine the psychometric characteristics of the Asthma Quality of Life Questionnaire (AQLQ) in patients with difficult asthma, and (ii) to explore to what extent suffering from asthma affects the HRQL in patients with difficult asthma.
METHODS: Eighty-six adult patients with difficult asthma (33 men) participated in the study.
RESULTS: The internal consistency reliability (alpha) ranged from 0.80 (environment subscale) to 0.96 (overall score), and the 2- to 4-week reproducibility (intraclass correlation coefficients) ranged from 0.82 (environment subscale) to 0.92 (overall score). The AQLQ correlated significantly with an asthma disease severity scale, the EQ-5D, and the visual analogue scale indicator of global quality of life (P < 0.0001). No relationship was found between the AQLQ score and FEV1%.
CONCLUSIONS: The results suggest that the AQLQ may be a useful outcome measure for clinical trials in severe asthmatics. The results of this study showed that the HRQL in patients with difficult asthma is substantially impaired. The dominant feature of this group is high symptom scores, with environmental exposure scoring lowest. Mean AQLQ values for this group compared with published means from other less severe asthmatics suggest that patients with difficult asthma experience clinically significant, poorer health-related quality of life. This study presents the poorest health-related quality of life reported in patients with asthma.