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What is the Cochrane Collaboration?

The National Library of Medicine (NLM) worked with the Baltimore Cochrane Center and with the New England Cochrane Center (NECC) to improve access to information related to clinical trials in MEDLINE®. This effort started in 1995 and essentially involved the retrospective assignment of the specific Publication Type (PT) values of RANDOMIZED CONTROLLED TRIAL or CONTROLLED CLINICAL TRIAL to MEDLINE journal citations. The NECC coordinated the ongoing efforts of various Cochrane Centers, Review Groups, and others collaborating to identify citations to be enhanced, and provided this information to NLM on an annual basis through 2005. The NECC merged with two other Cochrane offices in December 2002 to form the United States Cochrane Center (USCC).

Much of the clinical trial identification work undertaken by the Cochrane Collaboration is on a voluntary basis. The USCC should have extensive information on which journals remain to be searched for clinical trial articles. Please also see the NLM Technical Bulletin (// beginning with the 1995 Mar-Apr;(283) issue and subsequent yearly indexes for more details. For example, collaborative activities are described in the NLM Technical Bulletin 2001 Nov-Dec;(323) issue and are excerpted below:

For the seventh year, NLM continued its work with the Cochrane Collaboration to enhance the identification of clinical trials in MEDLINE. For 2001 maintenance, the Cochrane identified over 7,200 MEDLINE citations to articles published from 1966-2001 to which the Randomized Controlled Trial or Controlled Clinical Trial Publication Type has been added. (Over 5,000 MEDLINE citations were similarly enhanced during 2000 maintenance.)

Also, NLM indexes the Cochrane Database of Systematic Reviews. More details are available at //

In addition to MEDLINE citations, the Cochrane Collaboration identifies citations related to clinical trials from journals (non-MEDLINE) found in other databases and provides access to this central registry via the Cochrane Library.

NLM is also working with the Cochrane Collaboration as an information partner for PubMed Health. See: //

For additional information on the Cochrane Collaboration activities, please see The Cochrane Library Web site ( or contact the United States Cochrane Center directly (