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Mental Health
Efficacy and effectiveness studies of depression are not well-differentiated in the literature: a systematic review
  1. Karen Schmaling1,
  2. Robert M Kaplan2,
  3. Franz Porzsolt3
  1. 1 Psychology, Washington State University, Vancouver, Washington, USA
  2. 2 Clinical Excellence Research Center, Stanford University School of Medicine, Stanford, California, USA
  3. 3 Institute of Clinical Economics, Ulm, Germany
  1. Correspondence to Dr Karen Schmaling, Psychology, Washington State University, Vancouver, Washington, DC 98686, USA; karen.schmaling{at}


Background In the literature on the treatment of depression, efficacy and effectiveness research have different purposes and should apply different research methodologies.

Objective The purpose of the study was to review characteristics of depression treatment studies identified using efficacy or effectiveness search terms. We considered subject inclusion and exclusion criteria; numbers of subjects enrolled and the proportion in the primary analyses; inclusion of a Consolidated Standards of Reporting Trials (CONSORT) flow diagram; use of random assignment; use of placebo control conditions; lengths of treatment and follow-up; primary outcome variable; trial registration; journal impact factor.

Study selection Studies indexed as efficacy AND ‘real-world’ AND depression or effectiveness AND ‘real-world’ AND depression in PubMed up to 18 May 2019.

Findings 27 studies met the inclusion criteria: 13 effectiveness studies, 6 efficacy studies and 8 studies indexed as both effectiveness and efficacy. Studies identified as effectiveness, efficacy, or both differed on three outcome measures: the inclusion criteria were lengthier for efficacy than for effectiveness studies; efficacy studies were more likely to have a placebo control condition than effectiveness studies; and the journal impact factor was lower for effectiveness studies than for studies from the efficacy search or studies identified by both searches.

Conclusions Efficacy and effectiveness research hypothetically use different methodologies, but the efficacy and effectiveness literatures in the treatment of depression were comparable for most of the coded characteristics. The lack of distinguishable characteristics suggests that variably applied terminology may hinder efforts to narrow the gap between research and practice.

PROSPERO registration number #CRD42019136840.

  • depression & mood disorders
  • clinical trials

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  • Contributors KS led the development of study concept, design, review protocol and drafted the manuscript; performed the searches and carried out the data extraction; and is the guarantor. RMK and FP provided critical input into the study design, concept, review protocol and edited the manuscript; and carried out data extraction. FP also reviewed abstracts for inclusion.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

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

  • Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. No additional data are available.