Objective: 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. Methods: 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. Results: 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. Conclusions: 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.Keywords: Asthma; Therapeutics; Diagnosis; Questionnaires; Reproducibility of results. ResumoObjetivo: Avaliar se a versão em língua portuguesa do Asthma Control Questionnaire (ACQ, Questionário de Controle da Asma) é um instrumento válido para medir o controle da asma em pacientes adultos ambulatoriais no Brasil. Métodos: Foram avaliados 278 pacientes ambulatoriais com diagnóstico de asma. Todos os pacientes, durante a primeira visita, responderam ao questionário, foram submetidos à espirometria e avaliados clinicamente por um médico para a caracterização do controle da doença. Foram analisadas as versões do questionário com 5, 6 e 7 questões, utilizando dois escores distintos (0,75 e 1,50) como pontos de corte. Resultados: Dos 278 pacientes, 77 (27,7%) tinham asma intermitente, 39 (14,0%) asma persistente leve, 40 (14,4%) asma persistente moderada e 122 (43,9%) asma persistente grave. A sensibilidade do questionário para identificar asma não-controlada variou de 77% a 99% e a especificidade variou de 36% a 84%. O valor preditivo positivo variou de 73% a 90%, e o valor preditivo negativo variou de 67% a 95%. A razão de verossimilhança positiva variou de 1,55 a 4,81, e a razão de verossimilhança negativa variou de 0,03 a 0,27. Nas versões do ACQ com 5 e 6 questões, o coeficiente de correlação intraclasse foi de 0,92, e estas versões foram responsivas a mudanças no quadro clínico dos pacientes. Conclusões: O ACQ, nas suas t...

The incidence of poor perception of asthma control in asthma patients is high, especially in elderly patients with lower income and a lower degree of asthma severity.