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CMAJ. 2014 Nov 4;186(16):E596-609. doi: 10.1503/cmaj.131693. Epub 2014 Sep 29.

Outcomes for patients with the same disease treated inside and outside of randomized trials: a systematic review and meta-analysis.

Author information

  • 1Faculty of Medicine (Natasha Fernandes, Mathur), University of Ottawa, Ottawa, Ont.; Faculty of Health Sciences (Bryant, Marsh, Moyer) and Schulich School of Medicine and Dentistry (Bryant), The University of Western Ontario, London, Ont.; Department of Clinical Epidemiology and Biostatistics (Bryant, Griffith), Department of Medicine (Nisha Fernandes), Health Sciences Library (Bhatnagar), Department of Family Medicine (Riva) and Division of Gynecologic Oncology (Reade), McMaster University, Hamilton, Ont.; Faculty of Dentistry (El-Rabbany), University of Toronto, Toronto, Ont.; School of Medical and Applied Sciences (Kean), Central Queensland University, Rockhampton, Australia; Department of Orthopaedic Surgery (Somerville), London Health Sciences Centre, London, Ont. natasha.fernandes31@gmail.com.
  • 2Faculty of Medicine (Natasha Fernandes, Mathur), University of Ottawa, Ottawa, Ont.; Faculty of Health Sciences (Bryant, Marsh, Moyer) and Schulich School of Medicine and Dentistry (Bryant), The University of Western Ontario, London, Ont.; Department of Clinical Epidemiology and Biostatistics (Bryant, Griffith), Department of Medicine (Nisha Fernandes), Health Sciences Library (Bhatnagar), Department of Family Medicine (Riva) and Division of Gynecologic Oncology (Reade), McMaster University, Hamilton, Ont.; Faculty of Dentistry (El-Rabbany), University of Toronto, Toronto, Ont.; School of Medical and Applied Sciences (Kean), Central Queensland University, Rockhampton, Australia; Department of Orthopaedic Surgery (Somerville), London Health Sciences Centre, London, Ont.

Abstract

BACKGROUND:

It is unclear whether participation in a randomized controlled trial (RCT), irrespective of assigned treatment, is harmful or beneficial to participants. We compared outcomes for patients with the same diagnoses who did ("insiders") and did not ("outsiders") enter RCTs, without regard to the specific therapies received for their respective diagnoses.

METHODS:

By searching the MEDLINE (1966-2010), Embase (1980-2010), CENTRAL (1960-2010) and PsycINFO (1880-2010) databases, we identified 147 studies that reported the health outcomes of "insiders" and a group of parallel or consecutive "outsiders" within the same time period. We prepared a narrative review and, as appropriate, meta-analyses of patients' outcomes.

RESULTS:

We found no clinically or statistically significant differences in outcomes between "insiders" and "outsiders" in the 23 studies in which the experimental intervention was ineffective (standard mean difference in continuous outcomes -0.03, 95% confidence interval [CI] -0.1 to 0.04) or in the 7 studies in which the experimental intervention was effective and was received by both "insiders" and "outsiders" (mean difference 0.04, 95% CI -0.04 to 0.13). However, in 9 studies in which an effective intervention was received only by "insiders," the "outsiders" experienced significantly worse health outcomes (mean difference -0.36, 95% CI -0.61 to -0.12).

INTERPRETATION:

We found no evidence to support clinically important overall harm or benefit arising from participation in RCTs. This conclusion refutes earlier claims that trial participants are at increased risk of harm.

PMID:
25267774
PMCID:
PMC4216275
DOI:
10.1503/cmaj.131693
[PubMed - indexed for MEDLINE]
Free PMC Article
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