Assessing the quality of information recorded on trial registries

Background: In 2004 all ICMJE member journals agreed to adopt a trial registrations policy as one solution to publication bias. The value of trial registries (TRs) has been well established and is supported by funding and government agencies. Yet there is little focus on the type and completeness of data in existing TRs. Objective: Our objectives were to, i) determine the type of data recorded in TRs, ii) assess their quality, iii) compare structure and content of different TRs, and iv) to identify optimal data structures for them. Design: In January 2005, a random sample of trial records was extracted from three international TRs ClinicalTrials.gov, NCI's PDQ Database and ISRCTN Register. No restrictions were placed on trial status, design or medical area, although some TRs adopted inclusion criteria. Records were assessed using a quality checklist consisting of 30 desirable items grouped into five categories, identifying information, trial details, funding, contact details and data collection forms. Results: A pilot study assessing 45 records (15 from each register) was undertaken. The overall quality was poor (median: 16 range: 10-22 items completed per record) and varied considerably across TRs. ClinicalTrial.gov (median 17) and NCIPDQ (median 18) faired better than ISRTCN (median 13) (ClinicalTrial.gov vs. NCIPDQ p=0.79; ClinicalTrial.gov vs. ISRTCN p<0.001; NCIPDQ vs. ISRTCN p