Aims of the study

Effectiveness and efficacy approximation

• The effectiveness and cost-effectiveness of solution-focused therapy, short-term psychodynamic psychotherapy, long-term psychodynamic psychotherapy and psychoanalysis are compared in an "intention to treat" approach, giving the clinical effect of the treatment policy.

• Proxy estimation of efficacy will be carried out using "as treated" analyses, taking into account compliance and use of auxiliary treatment.

Sufficiency research

• The treatability by short- versus long-term treatments will be studied through assessment of auxiliary psychiatric treatments (medication, psychotherapy and hospital treatment) and their determinants, during and after the study treatments.

Suitability research

• The prediction of patient-, therapist- and therapy-related factors on the outcome of short- and long-term psychotherapy is assessed to identify the circumstances under which patients need therapies of different length.

Methodological research

• Advanced statistical methods required for the implementation of the preceding research issues will be developed.

• Quality control was carried out to ensure the quality of the data collection during the long follow-up.

• The development of new measures will be carried out, as well as assessment of their reliability and agreement with other well-documented measures.

Qualitative study

• Study based on audio- and video-recorded baseline and follow-up interviews of patients, focused on gaining additional information and creating new hypotheses on patients’ experiences of the treatment.