Differential Effectiveness of Open Versus Closed Psychotherapy Groups: A Systematic Review

This systematic review aimed to provide an overview of the state of research on the effectiveness of open versus closed psychotherapy groups, from the beginning of empirical research on these groups to the present.

A literature search in seven databases and a supplementary search of the reference lists of 23 relevant articles were conducted between August 2022 and October 2023. Seventy-two articles were identified and screened for eligibility.

Twenty-seven articles met the inclusion criteria and were included in the review. Outcomes are reported by study design (randomized controlled trial, quasi-experimental, descriptive). Information on each study's sample, setting, types of groups, process versus outcome measures, and outcome evaluation is provided. Findings suggest that open and closed psychotherapy groups have the same effect on reducing symptoms of mental disorders. Perception of group cohesion was phase dependent in closed group therapies, whereas cohesion was perceived as more constant in open group therapies.

The question of how group therapy format may affect therapeutic outcomes and processes has been posed over the past 50 years, but trials are heterogeneous and robust conclusions cannot be made. Systematic research on the differential effectiveness of open versus closed psychotherapy groups is scarce. On the basis of empirical findings to date, no global superiority of either open or closed group therapy exists. Open and closed group therapies are equally effective, presumably because of different effect factors. An indication for open or closed group therapy must be made according to clinical requirements on a case-by-case basis.