Depression's influence on the Asthma Control Test, Japanese version.

Background: Depression has been linked to poorer asthma control in asthmatic patients. Although the Japanese version of the Asthma Control Test (ACT-J) is frequently used as a simple, practical evaluation tool in clinical care settings in Japan, knowledge regarding its efficacy for assessing asthma control in asthmatic patients with depression is limited. Thus, we retrospectively investigated cut-off values of the ACT-J for well-controlled asthma, and explored depression's influence on the test with a questionnaire survey. Methods: Data were analyzed on 1,962 adult asthmatic patients who had completed both the ACT-J and the Japanese version of the Patient Health Questionnaire-9 (J-PHQ-9) in 2008 questionnaire survey conducted by the Niigata Asthma Treatment Study Group. Patients were classified into low (LD: J-PHQ-9 score of 0-4) or high depression (HD: J-PHQ-9 score of 5-27) groups. In both groups, the efficacy of the ACT-J was confirmed. We then compared the optimal cut-off points for uncontrolled asthma in both groups by performing a receiver operating characteristic (ROC) analysis, using the original classification referred to the GINA classification as the "true" classification. Results: Cronbach's alpha in the LD and HD group was 0.808 and 0.740 respectively. In both groups, the subgroup with existence of work absenteeism or frequent attacks during the previous 12 months scored lower on the ACT-J. The area under the curve and optimal cut-off point for patients with LD and HD were 0.821 and 0.846, and 23 and 20 respectively. Conclusions: The efficacy of the ACT-J was confirmed in depressive patients with asthma. Because asthma control as evaluated with the ACT-J can be worse than actual control under depressive states, physicians should also pay attention to a patient's depressive state at evaluation. Further investigations focus on the association between the ACT-J and depression are required.