We aimed to explore the heterogeneity of schema therapy regarding (a) patient characteristics, (b) content, and (c) way of delivering schema therapy. A search was conducted of the electronic databases EMBASE, PsycINFO, Web of Science, MEDLINE, and COCHRANE up to June 15, 2022. Treatment studies were eligible if they (a) used schema therapy as (component of) the intervention examined, and (b) reported an outcome measure quantitatively. A total of 101 studies met the inclusion criteria, including randomized controlled trials (n = 30), non-randomized controlled trials (n = 8), pre-post designs (n = 22), cases series (n = 13), and case reports (n = 28), including 4006 patients. Good feasibility was consistently reported irrespective of format (group versus individual), setting (outpatient, day-treatment, inpatient), intensity of treatment, and the specific therapeutic components included. Schema therapy was applied to various (psychiatric) disorders. All studies presented promising results. Effectiveness of the different models of schema therapy as well as application beyond personality disorders should be examined more rigorously.
Keywords: heterogeneity; personality disorders; psychotherapy; schema therapy; systematic review.