Evaluation of the asthma control questionnaire validated for use in Brazil

To evaluate whether the Portuguese version of the Asthma Control Questionnaire (ACQ) is a valid instrument to measure asthma control in adult outpatients in Brazil.

We selected 278 outpatients diagnosed with asthma. All of the patients completed the questionnaire, underwent spirometry and were clinically evaluated by a physician in order to characterize the control of the disease in the first visit. The questionnaire was evaluated in three versions, with 5, 6 and 7 questions, respectively, and scores of 0.75 and 1.50 were used as cut-off points.

Of the 278 patients, 77 (27.7%) had intermittent asthma, 39 (14.0%) had mild persistent asthma, 40 (14.4%) had moderate persistent asthma and 122 (43.9%) had severe persistent asthma. The sensitivity of ACQ to identify uncontrolled asthma ranged from 77% to 99%, and the specificity ranged from 36% to 84%. The positive predictive value ranged from 73% to 90%, and the negative predictive value ranged from 67% to 95%. The positive likelihood ratio ranged from 1.55 to 4.81, and the negative likelihood ratio ranged from 0.03 to 0.27. In the 5- and 6-question versions of the ACQ, the intraclass correlation coefficient was 0.92. These two versions were both responsive to clinical changes in the patients.

All three versions of the ACQ satisfactorily discriminated between patients with uncontrolled asthma and those with controlled asthma. The 5- and 6-question versions also presented good reliability and responsiveness. Therefore, the ACQ is a valid tool for evaluating asthma control in adult outpatients in Brazil.