Intended for healthcare professionals

Education And Debate

Principles for international registration of protocol information and results from human trials of health related interventions: Ottawa statement (part 1)

BMJ 2005; 330 doi: (Published 21 April 2005) Cite this as: BMJ 2005;330:956

This article has a correction. Please see:

  1. Karmela Krleža-Jerić, clinical research officer (,
  2. An-Wen Chan, special advisor1,
  3. Kay Dickersin, professor2,
  4. Ida Sim, associate professor of medicine3,
  5. Jeremy Grimshaw, director4,
  6. Christian Gluud, head of Copenhagen trial unit5
  7. for the Ottawa Group
  1. 1 Randomised Controlled Trials Unit, Canadian Institutes of Health Research, Ottawa, 160 Elgin Street, Ottawa ON, K1A 0W9, Canada
  2. 2 Department of Community Health, Brown University, Providence, USA
  3. 3 Department of Medicine, University of California, San Francisco, USA
  4. 4 Clinical Epidemiology Program, Ottawa Health Research Institute, Ottawa, Canada
  5. 5 European Clinical Research Infrastructures Network, Copenhagen University Hospital, Copenhagen, Denmark
  1. Correspondence to: K Krleža-Jerić
  • Accepted 30 March 2005

Registering of trials is essential to make sure all results are publicly available and that ethical obligations to participants are met


Recent evidence of selective reporting of results has eroded public and academic confidence in publications of clinical trials, leading to renewed calls for trial registration.15 The dangers of non-disclosure of trial results, although described for years, sparked an international furore last spring after the publication of two systematic reviews on the effects of selective serotonin reuptake inhibitors for childhood depression.1 6 Subsequent legal proceedings7 and policy statements by journal editors,8 9 medical associations,10 and industry11 have recognised the importance of trial registration. The rationale for registering trials is well known (box 1).12 13 Most importantly, the contribution to social good that justifies research on human participants is not realised when resulting knowledge remains invisible.

As an interested and neutral party that has been registering the trials that it funds,14 the Canadian Institutes of Health Research hosted an open meeting on 4 October 2004 in Ottawa, Canada, to foster international consensus on trial registration. The resulting Ottawa statement aims to establish internationally recognised principles for registration (box 2). The full statement is on, but here we highlight and discuss some of the key principles. A statement on how to implement these principles (part 2) is still in development.

Summary of principles

The mandatory registration of all trials has three components:

  • Obtaining an internationally unique identification number (unique ID)

  • Registering the original protocol along with subsequent amendments

  • Registering the trial results.

Box 1: Rationale for registration of clinical trials


  • Respect the investigator-participant covenant to contribute to biomedical knowledge by making trial methods and results public

  • Provide global open access to information

  • Reduce unnecessary duplication of invested research resources through awareness of existing trials

  • Assure accountability with regard to global standards for …

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