Developing and Evaluating a Transdiagnostic Intervention for Mental Disorders Using the Common Elements Treatment Approach in Iranian Adults

Mental disorders contribute to a significant global disease burden worldwide. The present study aims to develop and evaluate a transdiagnostic intervention based on the common elements treatment approach (CETA) for mental disorders in Iranian adults.

This mixed-method study (qualitative/quantitative) was conducted in Semnan province, Iran. In the qualitative stage, interviews were conducted using the free listing technique with 20 community members and 10 key informants to extract the common mental disorders. Then, a tool for screening these disorders was designed, and its face validity, content validity, and criterion validity were determined. Next, the CETA-based transdiagnostic program for the treatment of these mental disorders was developed, and three training workshops on implementing the intervention program were held for 30 healthcare providers. Finally, a randomized clinical trial was conducted on 500 adults with mental disorders referred to health centers in Semnan province in two groups of intervention (receiving the CETA-based program) and control (routine treatment), and the effectiveness of the intervention was evaluated.

Three mental disorders, including depression, anxiety, and obsessive-compulsive disorder (OCD), were identified in the qualitative phase. The designed screening tool for measuring these disorders was a valid and reliable tool with 76 items. In this tool, the cut-off points for depression, anxiety, and OCD were 14, 17, and 6, respectively. In evaluating the effectiveness of transdiagnostic intervention, the results showed that the mean scores of depression (P<0.001), anxiety (P<0.001), and OCD (P<0.05) significantly decreased after intervention in both control and intervention groups, where the CETA-based intervention was more effective than the routine treatment. 

The CETA-based transdiagnostic intervention, delivered by healthcare providers to adults with depression, anxiety, and OCD, is a feasible and effective method and can be used to increase the mental health of adults in Iran.