Article Text

Disclosure of researcher allegiance in meta-analyses and randomised controlled trials of psychotherapy: a systematic appraisal
  1. Elena Dragioti1,
  2. Ioannis Dimoliatis1,
  3. Evangelos Evangelou1,2
  1. 1Department of Hygiene and Epidemiology, School of Medicine, University of Ioannina, University Campus, Ioannina, Greece
  2. 2Department of Epidemiology and Biostatistics, Imperial College London, London, UK
  1. Correspondence to Dr Evangelos Evangelou; vangelis{at}


Objective Psychotherapy research may suffer from factors such as a researcher’s own therapy allegiance. The aim of this study was to evaluate if researcher allegiance (RA) was reported in meta-analyses and randomised controlled trials (RCTs) of psychotherapeutic treatments.

Design Systematic approach using meta-analyses of different types of psychotherapies.

Data sources Medline, PsycINFO and Cochrane Database of Systematic Reviews.

Methods We evaluated meta-analyses of RCTs regarding various types of psychotherapies. Meta-analyses were eligible if they included at least one RCT with RA and they were published in journals in Medline, PsycINFO and Cochrane Database of Systematic Reviews with an impact factor larger than 5.

Results We identified 146 eligible meta-analyses that synthesised data from a total of 1198 unique RCTs. Only 25 of the meta-analyses (17.2%) reported allegiance and only 6 (4.1%) used a proper method to control its effect. Of the 1198 eligible primary RCTs, 793 (66.3%) were allegiant. Authors in 25 of these 793 RCTs (3.2%) reported their allegiance while only one study (0.2%) controlled for its effect.

Conclusions The vast majority among a group of published meta-analyses and RCTs of psychotherapeutic treatments seldom reported and evaluated the allegiance effect. The results of the present study highlight a major lack of this information in meta-analyses and their included studies, though meta-analyses perform slightly better than RCTs. Stringent guidelines should be adopted by journals in order to improve reporting and attenuate possible effects of RA in future research.

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:

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