An observational study found that authors of randomized controlled trials frequently use concealment of randomization and blinding, despite the failure to report these methods

Devereaux, P.J.; Choi, Peter T.-L.; El-Dika, Samer; Bhandari, Mohit; Montori, Victor M.; Schünemann, Holger J.; Garg, Amit X.; Busse, Jason W.; Heels-Ansdell, Diane; Ghali, William A.; Manns, Braden J.; Guyatt, Gordon H.

doi:10.1016/j.jclinepi.2004.03.017

« Previous Next »Journal of Clinical Epidemiology
Volume 57, Issue 12 , Pages 1232-1236, December 2004

An observational study found that authors of randomized controlled trials frequently use concealment of randomization and blinding, despite the failure to report these methods

P.J. Devereaux
- Department of Medicine, Department of Clinical Epidemiology and Biostatistics, Faculty of Health Sciences, McMaster University, Room 2C8, 1200 Main Street West, Hamilton, ON, L8N 3Z5, Canada
- Corresponding author. Tel: 905-525-9140 ext. 22804; fax: 905-524-3841.
Peter T.-L. Choi
- Department of Anesthesia and the Vancouver Coastal Health Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
Samer El-Dika
- Department of Medicine, State University of New York at Buffalo, Buffalo, NY, USA
Mohit Bhandari
- Department of Surgery, McMaster University, Hamilton, Ontario, Canada
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
Victor M. Montori
- Department of Medicine, Mayo Clinic, Rochester, MN, USA
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
Holger J. Schünemann
- Department of Medicine, State University of New York at Buffalo, Buffalo, NY, USA
- Department of Social and Preventive Medicine, State University of New York at Buffalo, Buffalo, NY, USA
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
Amit X. Garg
- Departments of Medicine and Epidemiology, University of Western Ontario, London, Ontario, Canada
Jason W. Busse
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
Diane Heels-Ansdell
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
William A. Ghali
- Departments of Medicine and Epidemiology, University of Western Ontario, London, Ontario, Canada
Braden J. Manns
- Departments of Medicine and Epidemiology, University of Western Ontario, London, Ontario, Canada
Gordon H. Guyatt
- Department of Medicine, Department of Clinical Epidemiology and Biostatistics, Faculty of Health Sciences, McMaster University, Room 2C8, 1200 Main Street West, Hamilton, ON, L8N 3Z5, Canada

Accepted 30 March 2004.

Abstract

Background and objective

Readers of randomized controlled trials (RCTs) commonly assume that what was not reported did not occur. We undertook an observational study to determine whether concealment of randomization or blinding was used in RCTs that failed to report these bias-reducing strategies.

Methods

We recorded the reporting of concealment of randomization and blinding in 105 RCTs. We subsequently contacted the authors and determined if they had used these methodological safeguards.

Results

We successfully obtained data from 98 authors. The authors in the full-text publications of these 98 RCTs failed to report the presence or absence of concealment of randomization in 55%, and the blinding status of participants in 26%, health care providers in 64%, data collectors in 84%, outcome assessors in 83%, and data analysts in 96%. In direct contact, authors frequently reported concealing randomization (96%; 95% confidence interval CI=87–100%), blinding participants (20%; 95% CI=7–41%), blinding health care providers (65%; 95% CI=52–77%), blinding data collectors (65%; 95% CI=53–75%), blinding outcome assessors (79%; 95% CI=69–87%), and blinding data analysts (50%; 95% CI=40–60%), despite not reporting the use of these methodological safeguards in their publications.