Measuring disease-specific quality of life in obstructive airway disease: validation of a modified version of the airways questionnaire 20.
BACKGROUND
The Airways Questionnaire 20 (AQ20) is a concise measure of health-related quality of life (HRQL) in obstructive airway disease; however, its original format may underestimate impairment due to the complete cessation of certain activities.


METHODS
We revised seven items of the original AQ20 (revised AQ20 [AQ20-R]), adding response options for inability to perform certain activities. We assessed the performance of the AQ20-R among 352 adults with various airway conditions identified through a random telephone sample. Concurrent validity of the AQ20-R was assessed relative to the Short Form-12 (SF-12) physical component summary (PCS), FEV(1), and medication use. Predictive validity was assessed relative to health-care utilization among 278 subjects studied longitudinally.


RESULTS
Twenty-one of 352 subjects were unable to perform at least one activity. These subjects demonstrated higher AQ20-R scores (p < 0.001) indicating worse HRQL. Mean (+/- SD) AQ20-R scores differed significantly (p < 0.001) among subjects with COPD (8.9 +/- 5.2), asthma (6.7 +/- 5.0), and chronic bronchitis (4.7 +/- 4.2). At baseline, the AQ20-R correlated with the SF-12 PCS (r = - 0.55, p < 0.001) and FEV(1) (r = - 0.43, p < 0.001), and was associated with the use of respiratory-specific therapies (p </= 0.001). In multivariate models, the AQ20-R was an independent predictor of outpatient visits (odds ratio, 2.2; 95% confidence interval, 1.6 to 3.1), emergency department visits (odds ratio, 2.9; 95% confidence interval, 1.9 to 4.6), hospitalization (odds ratio, 2.8; 95% confidence interval, 1.6 to 4.9), and ICU admission (odds ratio, 3.0; 95% confidence interval, 1.2 to 7.3) during the following year.


CONCLUSIONS
The AQ20-R is a valid respiratory-specific HRQL measure that accounts for activity cessation among the most impaired and can be used across various airway conditions.
Chen
Hubert
H
Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94143-0924, USA. hubert.chen@ucsf.edu
Eisner
Mark D
MD
Katz
Patricia P
PP
Yelin
Edward H
EH
Blanc
Paul D
PD
D000368:Aged; D005260:Female; D005541:Forced Expiratory Volume; D006296:Health Services / Q000706:statistics & numerical data; D006304:Health Status; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000503:physiopathology* / Q000523:psychology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D011788:Quality of Life; D015203:Reproducibility of Results; D019141:Respiratory System Agents / Q000008:administration & dosage; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
D019141:Respiratory System Agents