Development of the Transdiagnostic Skills Scale (T2S).

Introduction: Psychotherapy has proved its efficacy for treating a wide range of psychological disorders. Most types of psychotherapy have been developed to treat specific disorders and validated through controlled-randomized trials. In recent years, researchers have developed a new way to conceptualize patients' difficulties, focusing on processes instead of diagnoses. However, there is no simple scale that evaluates transdiagnostic processes, and the development of such a tool is thus the aim of this study.

Method: We identified 12 processes that can be targeted in cognitive behavior therapy and created the Transdiagnostic Skills Scale (T2S) to evaluate them. We measured its internal consistency, factor structure and convergent validity in clinical and non-clinical samples.

Results: We found a 6-factor structure composed of emotion regulation, behavioral activation/planning, emotional identification, assertiveness, problem solving and emotional confrontation. The T2S has high internal consistency (Cronbach's alpha = 0.95). We found negative associations between skills and symptoms of anxiety, depression and eating disorders. We found no association between these processes and symptoms of either alcohol or cannabis use disorder.

Conclusions: The T2S is a useful and valid tool to identify the skills that clinicians should work on with their patients. It offers a complementary way to understand patients' difficulties when categorical assessment is complicated.