Validation and agreement across four versions of the asthma control questionnaire in patients with persistent asthma

Objective: The objectives of this study were to: 1) examine the psychometric properties of three shortened versions of the Asthma Control Questionnaire (ACQ) and their comparative performance with the original 7-item ACQ in persistent asthma patients; and 2) explore the concordance of asthma control outcomes from the four versions of the ACQ when compared with international guidelines for asthma control. Method: Post-hoc analyses of two large (n = 737 and n = 772) Phase III, randomized, double-blind, parallel-group, multi-center placebo-controlled studies of mometasone furoate/formoterol fumarate combination formulation compared with monotherapies in subjects with persistent asthma previously treated with low-dose or medium-dose inhaled glucocorticoids. This study examined the psychometric performance of the four ACQ versions and the concordance between these four versions with each other and international guidelines. Results: The psychometric results for all four versions of the ACQ were robust, with Cronbach alphas >= 0.82 and test-retest ICCs >= 0.75. All versions of the ACQ were strongly correlated with each other (r >= 0.97), as well the overall score from the AQLQ12+ for both baseline and change scores (vertical bar r vertical bar >= 0.74). When the four ACQ versions were compared to each other, both cross sectional and longitudinal change concordances were mostly substantial, but agreements were lower when compared to international guidelines classifications. Conclusion: All ACQ versions have similar and strong psychometric properties. Classifications of change over time using the original ACQ and a six-item version without SABA use provided generally fair to moderate agreement with the international guidelines criteria for asthma control. (C) 2011 Elsevier Ltd. All rights reserved.