Evaluation of the Asthma Life Quality test for the screening and severity assessment of asthma

Background: Asthma Life Quality (ALQ) test, a 20-question questionnaire developed by the American College of Allergy, Asthma and Immunology, has been shown to be useful for asthma diagnosis. We aimed to determine the relation between ALQ scores and (a) diagnosis of asthma; (b) physician's classification of asthma severity according to National Institutes of Health/Global Initiative for Asthma (GINA). Methods: Standard translation and cultural adaptation to Portuguese was performed. Patients self-administered the ALQ in the waiting room; the attending allergist classified them, blindly for the test. The scores of nonasthmatics were compared with those of asthma patients. Asthma patients were analyzed in two severity groups: intermittent and mild persistent asthma (IMPA), and moderate and severe persistent asthma (MSPA); sensitivity, specificity, positive and negative predictive values were calculated and receiver operating characteristic curve plotted. Logistic regression analysis models were computed. Results: From 283 patients, 237 tests were analyzed. Non-asthmatic patients ALQ scores (mean +/- SD) were 6 +/- 4 and, for asthmatics, 10 +/- 5 [mean difference 4.6 (95%CI 3.3-5.9)]. The odds of positive diagnosis increased 1.27 times (95%CI 1.17-1.38) for each one-unit increase in the test. For asthma severity ALQ scores were 9 +/- 4 for IMPA, 15 +/- 3 for MSPA [difference 6.0 (95%CI 4.8-7.1)]; with a sensitivity of 88% and specificity of 74% for a score of 12. The odds of MSPA increased 1.49 times (95%CI 1.28-1.74) per unit increase in ALQ. Conclusions: ALQ can help both to identify patients with asthma and to differentiate those more likely to have moderate/severe asthma. These are relevant characteristics for the possible use of this simple, self-administered questionnaire in the assessment of asthma patients needing additional medical management.