Article type
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Abstract
Background: Since 1995, the Cochrane Collaboration has been developing a centralized register of controlled trials and other studies of healthcare interventions (called CENTRAL) to ensure that Collaborative Review Groups have access to as high a proportion as possible of all records that relate to studies that might be eligible for inclusion in Cochrane Reviews. CENTRAL serves as a source of trials to be searched by Collaborative Review Groups to identify trials for their own subject matter-specific ("specialized") trials registers. These specialized registers, in turn, ensure that individual reviewers within a Collaborative Review Group have easy and reliable access to as many trials as possible relevant to their review topic.
Methods: Broad CENTRAL record eligibility criteria were agreed in 1992. CENTRAL is recreated anew for each quarterly release of The Cochrane Library by merging the most recently submitted version of each of the Collaborative Review Groups' specialized registers; a register of trial reports identified by page-by-page handsearches of health-related journals; and registers of reports downloaded from electronic bibliographic databases (e.g., MEDLINE and EMBASE). Because of the methods used in its development, CENTRAL is not a fixed, stable electronic bibliographic database but rather an amalgamation of multiple smaller, ever-changing, independent component registers.
Results: Several lessons have been learned in developing CENTRAL: 1) A clear and transparent manual should document the processes used by the developers (e.g., the New England Cochrane Center, Providence Office and Update Software) as well as the procedures to be followed by contributors; 2) Contributors should download available records from electronic bibliographic databases when appropriate permissions have been obtained; 3) All people who submit records should be well-trained trials search coordinators who can assure the quality of their submissions, and if resources are available, a duplicate quality check should be performed centrally; 4) All files transferred among different groups participating in this collaborative project should conform to agreed file structures and definitions; and 5) Definitions of eligibility criteria for the centralized register should be established early on, and refined and expanded as necessary.
Some ongoing challenges include reducing the number of duplicate citations and preventing submission and inclusion of citations that do not meet the eligibility criteria for CENTRAL. Efforts underway to meet these challenges will be reviewed.
Conclusions: Many lessons have been learned in developing CENTRAL and some of these may serve to inform similar projects under development (e.g., the Campbell Collaboration's Social, Psychological, Educational, and Criminological Trials Register (SPECTR) and the European Union Psi-Tri Project).
Methods: Broad CENTRAL record eligibility criteria were agreed in 1992. CENTRAL is recreated anew for each quarterly release of The Cochrane Library by merging the most recently submitted version of each of the Collaborative Review Groups' specialized registers; a register of trial reports identified by page-by-page handsearches of health-related journals; and registers of reports downloaded from electronic bibliographic databases (e.g., MEDLINE and EMBASE). Because of the methods used in its development, CENTRAL is not a fixed, stable electronic bibliographic database but rather an amalgamation of multiple smaller, ever-changing, independent component registers.
Results: Several lessons have been learned in developing CENTRAL: 1) A clear and transparent manual should document the processes used by the developers (e.g., the New England Cochrane Center, Providence Office and Update Software) as well as the procedures to be followed by contributors; 2) Contributors should download available records from electronic bibliographic databases when appropriate permissions have been obtained; 3) All people who submit records should be well-trained trials search coordinators who can assure the quality of their submissions, and if resources are available, a duplicate quality check should be performed centrally; 4) All files transferred among different groups participating in this collaborative project should conform to agreed file structures and definitions; and 5) Definitions of eligibility criteria for the centralized register should be established early on, and refined and expanded as necessary.
Some ongoing challenges include reducing the number of duplicate citations and preventing submission and inclusion of citations that do not meet the eligibility criteria for CENTRAL. Efforts underway to meet these challenges will be reviewed.
Conclusions: Many lessons have been learned in developing CENTRAL and some of these may serve to inform similar projects under development (e.g., the Campbell Collaboration's Social, Psychological, Educational, and Criminological Trials Register (SPECTR) and the European Union Psi-Tri Project).