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Individual patient data meta-analysis of combined treatments versus psychotherapy (with or without pill placebo), pharmacotherapy or pill placebo for adult depression: a protocol
  1. Erica Weitz1,
  2. Annet Kleiboer1,
  3. Annemieke van Straten1,
  4. Steven D Hollon2,
  5. Pim Cuijpers1
  1. 1Department of Clinical, Neuro and Developmental Psychology, and EMGO Institute for Health and Care Research, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
  2. 2Department of Psychology, Vanderbilt University, Nashville, Tennessee, USA
  1. Correspondence to Erica Weitz; e.weitz{at}


Introduction There are many proven treatments (psychotherapy, pharmacotherapy or their combination) for the treatment of depression. Although there is growing evidence for the effectiveness of combination treatment (psychotherapy + pharmacotherapy) over pharmacotherapy alone, psychotherapy alone or psychotherapy plus pill placebo, for depression, little is known about which specific groups of patients may respond best to combined treatment versus monotherapy. Conventional meta-analyses techniques have limitations when tasked with examining whether specific individual characteristics moderate the effect of treatment on depression. Therefore, this protocol outlines an individual patient data (IPD) meta-analysis to explore which patients, with which clinical characteristics, have better outcomes in combined treatment compared with psychotherapy (alone or with pill placebo), pharmacotherapy and pill placebo.

Methods and Analysis Study searches are completed using an established database of randomised controlled trials (RCTs) on the psychological treatment of adult depression that has previously been reported. Searches were conducted in PubMed, PsycInfo, Embase and the Cochrane Central Register of Controlled Trials. RCTs comparing combination treatment (psychotherapy + pharmacotherapy) with psychotherapy (with or without pill placebo), pharmacotherapy or pill placebo for the treatment of adult depression will be included. Study authors of eligible trials will be contacted and asked to contribute IPD. Conventional meta-analysis techniques will be used to examine differences between studies that have contributed data and those that did not. Then, IPD will be harmonised and analysis using multilevel regression will be conducted to examine effect moderators of treatment outcomes.

Dissemination Study results outlined above will be published in peer-reviewed journals. Study results will contribute to better understanding whether certain patients respond best to combined treatment or other depression treatments and provide new information on moderators of treatment outcome that can be used by patients, clinicians and researchers.

Trial registration number CRD42016039028.

  • Systematic Review
  • meta-analysis

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  • Contributors PC, EW, AK, AvS and SDH conceptualised and designed the study. EW drafted the manuscript. EW, AK, AvS, SH and PC critically revised the manuscript). All authors have read and approved the final manuscript.

  • Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Ethics approval This article describes a study protocol for an individual participant data meta-analysis. This study requires no ethical approval. Study results outlined above will be published in peer-reviewed journals. Anonymised data collected during the data acquisition phase of this study will be managed by EW and will be available to the entire research team.

  • Provenance and peer review Not commissioned; externally peer reviewed.