Study designs
Three different study designs were used: a randomized clinical trial and a quasi-experimental study for effectiveness and treatability/sufficiency research and cohort study for suitability research.
Randomized clinical trial
In the randomized clinical trial, which consisted of 326 patients, the eligible patients were randomly assigned to solution-focused therapy (97 patients), short-term psychodynamic psychotherapy (101 patients), and long-term psychodynamic psychotherapy (128 patients).
Quasi-experimental design
The quasi-experimental design consisted of 367 patients: 326 were patients randomly assigned to either short-term or long-term psychotherapy and 41 patients were self-selected and assessed to be suitable for psychoanalysis.
Suitability research
The suitability applications, used to predict the effect of patient-, therapist-, and therapy-related factors, were observational cohort studies.
Sample size: Intention-to-treat and as treated
| Form of therapy | Intention-to-treat | As treated |
|---|---|---|
| Short-term solution-focused therapy | 97 | 93 |
| Short-term psychodynamic psychotherapy | 101 | 98 |
| Long-term psychodynamic psychotherapy | 128 | 102 |
| Psychoanalysis | 41 | 40 |
| Total | 367 | 333 |
