Aims: To determine the reliability and validity of the Asthma Control Test (ACT) to detect Global Initiative for Asthma (GINA)-defined uncontrolled or partly controlled asthma, and to determine the agreement between ACT and GINA in classifying asthma control among Vietnamese patients.
Methods: A cross-sectional study was performed in 323 of 360 invited outpatients with asthma in Ho Chi Minh City to compare the ACT and GINA classification for asthma control.
Results: Internal consistency of the ACT (Cronbach's alpha) was 0.83. The kappa coefficient of 0.55, based on the ternary split, represents moderate agreement between the two rating systems with a correctly classified rate of 75%. The area under the receiver operating characteristics curve for the ACT score predicting GINA control was 0.85. To detect GINA-defined 'not controlled asthma', the ACT had a sensitivity of 70%, specificity of 93%, and a positive predictive value of 89%, with a cut-off point of 19. The validity of the ACT with regard to agreement with the GINA classification was consistent across both sexes, but less so in adolescents or younger adults. The ACT score was significantly correlated with the percentage predicted forced expiratory volume in 1 second (r=0.35, p<0.001) and percentage predicted peak expiratory flow (r=0.26, p<0.001).
Conclusions: The Vietnamese ACT is useful for identifying outpatients with GINA-defined uncontrolled or partly controlled asthma.