Allegiance Bias and Treatment Quality as Moderators of the Effectiveness of Humanistic Psychotherapy: Protocol for a Systematic Review and Meta-Analysis

Background: In many countries, humanistic psychotherapy (HPT) is viewed as a broad psychotherapeutic approach and is accepted in health care systems. To qualify for reimbursement by health insurance in Germany, psychotherapy approaches have to be evaluated positively by the German Scientific Board of Psychotherapy (GSBP). The GSBP examined HPT and its subapproaches based on an application by a number of professional organizations affiliated with HPT (Work Group Humanistic Psychotherapy, WGHPT). The GSBP came to the decision that none of the HPT subapproaches provided sufficient evidence to be evaluated as evidence based. Potential reasons for the discrepancy between international recognition of HPT and GSBP's decision will be explored: researchers' allegiance may have led to a risk of bias disadvantaging HPT. Furthermore, the evaluation criteria of the GSBP did not systematically consider whether HPT was conceptualized bona fide and implemented with sufficient treatment integrity in the studies. Objective: This systematic review will re-examine the studies included in the review of the GSBP. Within 2 comparisons (HPT vs control and HPT vs other psychotherapeutic interventions), we will examine moderating effects of treatment quality (bona fide and treatment integrity) and allegiance on the effectiveness of HPT. Methods: This review is based on the prior systematic review by the GSBP. The GSBP examined randomized controlled trials (RCTs) and studies with non-RCTs of HPT interventions for individuals with mental disorders. All studies suggested by the WGHPT were included; moreover, the GSBP conducted searches in standard electronic databases (Cochrane Central Register of Controlled Trials, MEDLINE, PsycINFO, and PSYNDEX) and handsearches in relevant systematic reviews and contacted experts. A total of 2 independent GSBP reviewers performed study screening using a structured form. On the basis of the prior work of the GSBP, all studies that were positively screened by the GSBP will be included in this review. Data will be extracted independently by 4 authors Standardized mean difference will be calculated, and possible publication bias will be tested using funnel plots and Egger test. A priori defined subgroup or meta-regression analyses will be performed for treatment quality, allegiance, type of nonactive control, study quality, type of subapproach, and target population (children and adolescents or adults). Results: The GSBP identified 115 eligible studies that will be reanalyzed in this systematic review. Conclusions: Results about moderator effects of treatment quality and allegiance will provide important information about their impact on the evaluation of HPT and other psychotherapy approaches and can be used for further evaluation methods.