Is the Allegiance Effect an Epiphenomenon of True Efficacy Differences between Treatments? A Meta-Analysis

Autor/inn/en	Munder, Thomas; Fluckiger, Christoph; Gerger, Heike; Wampold, Bruce E.; Barth, Jurgen
Titel	Is the Allegiance Effect an Epiphenomenon of True Efficacy Differences between Treatments? A Meta-Analysis
Quelle	In: Journal of Counseling Psychology, 59 (2012) 4, S.631-637 (7 Seiten) PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	0022-0167
DOI	10.1037/a0029571
Schlagwörter	Validity; Posttraumatic Stress Disorder; Psychotherapy; Effect Size; Researchers; Meta Analysis; Comparative Analysis; Outcomes of Treatment; Correlation + Suchen Sie Ihr Suchwort? Gültigkeit; Psychotherapie; Researcher; Forscher; Meta-analysis; Metaanalyse; Korrelation
Abstract	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. (Contains 2 tables and 2 footnotes.) (As Provided).
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Update	2017/4/10