Across the world today, psychotherapy face challenges that mainly concern the issue of demonstrating its effectiveness based on evidence. As in medicine, in psychotherapy it is undisputed that objective, reliable findings on the effects of psychotherapy are necessary. In contrast to other countries, in Switzerland there is still a great diversity of different psychotherapy approaches. This presents a unique opportunity to evaluate different therapeutic approaches on the basis of the same effectiveness criteria (independent of theory) and to place the effectiveness in relation to the methods specific to the different schools of therapy. enschaft, 2, 96-107.

1. What is the general benefit of the different therapy methods?
2. Can specific effectiveness be demonstrated in a comparison of different treatment approaches?
3. Is there evidence indicating what therapy methods are particularly appropriate for what patients and what diagnoses?

Eleven psychotherapy associations or schools under the umbrella of the Swiss Charter for Psychotherapy (Schweizer Charta für Psychotherapie) agreed to participate in an empirical study of the effectiveness of their treatments. The study design is a naturalistic one. This is the best suited design to depict the real therapeutic work in outpatient practice, which makes up a large part of the treatment of mental disorders. Most effectiveness studies are conducted under laboratory conditions, because in this way it is easier to control the research conditions and variables. The internal validity of this so-called controlled research is higher; however, the drawback of the controlled trial is that it can hardly deliver knowledge about forms of treatment actually used in real practice, and these facts are therefore lacking for health policy and science policy discussions.
The PAP-S Study (Psychotherapiestudie Ambulante Psychotherapie Schweiz) is designed as a process-outcome study. In a sample, parameters of various dimensions are assessed by external experts at three time points (at the start and conclusion of therapy and one year after the end of therapy). Also during therapy additional data are reported by therapists and patients. The outcome and process measurements are thus obtained from three perspectives: patient, therapist, and external experts. The reliability of the experts (interrater reliability) is checked continuously. Any medication use by patients during the course of therapy is also recorded. Standardized and widely recognized measuring instruments in psychotherapy research, originally developed in different basic approaches, are used for all of the forms of therapy. To check what therapy method and mixed methods were actually used in a particular course of therapy, an instrument was developed specifically for this study.

The study duration is 7 years (2006-2012), so that not only short-course therapies but also longer course therapies can be assessed. It is planned to examine a total of 350 patient therapies; for one, this will allow analysis specific to each institution, and for another, it will ensure a statistically sufficient number of patients per mainstream (humanistic, psychodynamic, body-oriented therapy forms), so that the comparative effectiveness of different therapy approaches with comparable patients can be appraised. Initial findings of the PAP-S Study were presented at the 20th IPF IFP World Congress of Psychotherapy in June 2010 and published in an article in Psychotherapie Forum.

• von Wyl, A., Crameri, A., Koemeda, M., Tschuschke, V., Schulthess, P. (2013). Praxisstudie ambulante Psychotherapie Schweiz (PAP-S): Studiendesign und Machbarkeit. Psychotherapie-Wissenschaft, 1, 6-22.
• von Wyl, A., Crameri, A., Koemeda, M., Tschuschke, V., Schulthess, P. (2013). The PAP-S (Practice of Ambulant Psychotherapy-Study), Switzerland : study design and feasibility, ZHAW Zürcher Hochschule für Angewandte Wissenschaften.
• Crameri, A., von Wyl, A., Koemeda, M., Schulthess, P. & Tschuschke, V. (2015). Sensitivity analysis in multiple imputation in effectiveness studies of psychotherapy. Frontiers in Psychology, 6, doi: 10.3389/fpsyg.2015.01042.
• Crameri, A., Koemeda, M., Tschuschke, V., Schulthess, P. & von Wyl, A. (2014). Ergebnisqualität ambulanter Psychotherapie. Ergebnisse aus der Grundversorgung in der Schweiz. Psychotherapie-Wiss

Universität Köln, Schweizer Charta für Psychotherapie