title: Testing the allegiance bias hypothesis: a meta-analysis.
abstract: This meta-analysis investigated whether the association between researcher allegiance (RA) and the relative effect of two psychotherapies can be explained through the methodological weaknesses of the treatment comparisons. Seventy-nine comparisons of psychotherapies for depression or posttraumatic stress disorder (PTSD) were included. Methodological quality (MQ) was investigated as both a moderator and a mediator of the RA-outcome association. MQ included balanced nonspecific factors, balanced specific factors, conceptual quality, patients-per-therapist ratio, randomization to conditions and outcome assessment. The RA-outcome association was stronger when the MQ was low, suggesting a buffering effect of MQ. In addition, differences in the conceptual quality of treatments mediated the effect of RA on outcome. The results support the view that RA acts as a bias in treatment comparisons.
authors.affiliation: Institute of Social and Preventive Medicine-ISPM, University of Bern, Bern, Switzerland. tmunder@ispm.unibe.ch
authors.forename: Thomas
authors.initials: T
authors.lastname: Munder
authors.forename: Heike
authors.initials: H
authors.lastname: Gerger
authors.forename: Sven
authors.initials: S
authors.lastname: Trelle
authors.forename: Jürgen
authors.initials: J
authors.lastname: Barth
mesh_terms: D000328:Adult; D015982:Bias; D003866:Depressive Disorder / Q000628:therapy; D006801:Humans; D011613:Psychotherapy / Q000379:methods / Q000592:standards; D012108:Research Personnel / Q000523:psychology*; D013313:Stress Disorders, Post-Traumatic / Q000628:therapy; D016896:Treatment Outcome