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 sub-group 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.