Chest
Volume 115, Issue 5, May 1999, Pages 1265-1270
Journal home page for Chest

Clinical Investigations
ASTHMA
Validation of a Standardized Version of the Asthma Quality of Life Questionnaire

https://doi.org/10.1378/chest.115.5.1265Get rights and content

Background

In the original 32-item Asthma Quality of Life Questionnaire (AQLQ), five activity questions are selected by patients themselves. However, for long-term studies and large clinical trials, generic activities may be more appropriate.

Methods

For the standardized version of the AQLQ, the AQLQ(S), we formulated five generic activities (strenuous exercise, moderate exercise, work-related activities, social activities, and sleep) to replace the five patient-specific activities in the AQLQ. In a 9-week observational study, we compared the AQLQ with the AQLQ(S) and examined their measurement properties. Forty symptomatic adult asthma patients completed the AQLQ(S), the AQLQ, the Medical Outcomes Survey Short Form 36, the Asthma Control Questionnaire, and spirometry at baseline, 1, 5, and 9 weeks.

Results

Activity domain scores (mean ± SD) were lower with the AQLQ (5.7 ± 0.9) than with the AQLQ(S) (5.9 ± 0.8; p = 0.0003) and correlation between the two was moderate (r = 0.77). However, for overall scores, there was minimal difference (AQLQ, 5.4 ± 0.8; AQLQ(S), 5.5 ± 0.8; r = 0.99). Reliability (AQLQ intraclass correlation coefficient, 0.95; AQLQ(S) intraclass correlation coefficient, 0.96) and responsiveness (AQLQ, p < 0.0001; AQLQ(S), p < 0.0001) were similar for the two instruments. Construct validity (correlation with other measures of health status and clinical asthma) was also similar for the two instruments.

Conclusions

The AQLQ(S) has strong measurement properties and is valid for measuring health-related quality of life in asthma. The choice of instrument should depend on the task at hand.

Section snippets

Formulation of the Five Generic Activities

Our aim was to formulate five generic activity questions that would cover the activities that are most frequently identified by asthma patients as being the most troublesome in their day-to-day lives. In addition, we wanted to ensure that the balance of the five questions (physical, social, occupational) reflects the frequency with which the activities are identified by patients. We reviewed the original item reduction data from the development of the AQLQ1 and a number of clinical trial

Results

All 40 patients completed the first three assessments; 1 patient failed to return for the final visit. Demographic data are shown in Table 2.

Discussion

The results of this study provide evidence that the AQLQ(S) is a valid instrument for measuring health-related quality of life in adults with asthma. We evaluated validity in two ways: first, by determining the level of concordance (agreement) between the AQLQ(S) and the AQLQ (criterion validity); and, second, by comparing the measurement properties of the two instruments (construct validity).

The concordance analysis showed that the mean score for the activity domain of the AQLQ(S) was

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