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

Description

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.

Format

Journal

Language

English

Author(s)

Thomas Munder
Christoph Fluckiger
Heike Gerger
Bruce E. Wampold
Jurgen Barth

Original Work Citation

Munder, T., Fluckiger, C., Gerger, H., Wampold, B. E., & Barth, J. (2012, October). Is the allegiance effect an epiphenomenon of true efficacy differences between treatments? A meta-analysis. Journal of Counseling Psychology, 59(4), 631-637. doi:10.1037/a0029571

Collection

Citation

“Is the allegiance effect an epiphenomenon of true efficacy differences between treatments? A meta-analysis,” Francine Shapiro Library, accessed October 26, 2020, https://emdria.omeka.net/items/show/21872.

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