Is the allegiance effect an epiphenomenon of true efficacy differences between treatments? a meta-analysis

Munder, Thomas; Flückiger, Christoph; Gerger, Heike; Wampold, Bruce E; Barth, Jürgen (2012). Is the allegiance effect an epiphenomenon of true efficacy differences between treatments? a meta-analysis. Journal of counseling psychology, 59(4), pp. 631-7. Dubuque, Iowa: American Psychological Association 10.1037/a0029571

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Many meta-analyses of comparative outcome studies found a substantial association of researcher allegiance (RA) and relative treatment effects. Therefore, RA is regarded as a biasing factor in comparative outcome research (RA bias hypothesis). However, the RA bias hypothesis has been criticized as causality might be reversed. That is, RA might be a reflection of true efficacy differences between treatments (true efficacy hypothesis). Consequently, the RA-outcome association would not be indicative of bias but an epiphenomenon of true efficacy differences. This meta-analysis tested the validity of the true efficacy hypothesis. This was done by controlling the RA-outcome association for true efficacy differences by restricting analysis to direct comparisons of treatments with equivalent efficacy. We included direct comparisons of different versions of trauma-focused therapy (TFT) in the treatment of posttraumatic stress disorder (PTSD). RA was measured from the research reports. Relative effect sizes for symptoms of PTSD were calculated. Random effects meta-regression was conducted. Twenty-nine comparisons of TFTs from 20 studies were identified. Initial heterogeneity among relative effect sizes was low. RA was a significant predictor of outcome and explained 12% of the variance in outcomes. The true efficacy hypothesis predicted the RA-outcome association to be zero; however, a substantial association was found. Thus, this study does not support the true efficacy hypothesis. Given findings from psychotherapy research and other fields that support a biasing influence of researcher preferences, RA should be regarded as a causal factor and conceptualized as a threat to the validity of conclusions from comparative outcome studies.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Social and Preventive Medicine (ISPM)

UniBE Contributor:

Munder, Thomas, Gerger, Heike, Barth, Jürgen

Subjects:

600 Technology > 610 Medicine & health

ISSN:

0022-0167

Publisher:

American Psychological Association

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:35

Last Modified:

05 Dec 2022 14:11

Publisher DOI:

10.1037/a0029571

PubMed ID:

22946981

Web of Science ID:

000310126800013

BORIS DOI:

10.7892/boris.13932

URI:

https://boris.unibe.ch/id/eprint/13932 (FactScience: 220650)

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