Journal Article

Both clinical trial register and electronic bibliographic database searches were needed to identify randomized clinical trials for systematic reviews: an evaluation study

Kaul, Tabea, Colombijn, Julia M.T., Vernooij, Robin W.M., Spijker, Rene, Damen, Johanna A.A., Hooft, Lotty, Idema, Demy L., Huis in ‘t Veld, Linde F.

2024

Overview

To determine whether clinical trial register (CTR) searches can accurately identify a greater number of completed randomized clinical trials (RCTs) than electronic bibliographic database (EBD) searches for systematic reviews of interventions, and to quantify the number of eligible ongoing trials. We performed an evaluation study and based our search for RCTs on the eligibility criteria of a systematic review that focused on the underrepresentation of people with chronic kidney disease in cardiovascular RCTs. We conducted a combined search of ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform through the Cochrane Central Register of Controlled Trials to identify eligible RCTs registered up to June 1, 2023. We searched Cochrane Central Register of Controlled Trials, EMBASE, and MEDLINE for publications of eligible RCTs published up to June 5, 2023. Finally, we compared the search results to determine the extent to which the two sources identified the same RCTs. We included 92 completed RCTs. Of these, 81 had results available. Sixty-six completed RCTs with available results were identified by both sources (81% agreement [95% CI: 71–88]). We identified seven completed RCTs with results exclusively by CTR search (9% [95% CI: 4–17]) and eight exclusively by EBD search (10% [95% CI: 5–18]). Eleven RCTs were completed but lacked results (four identified by both sources (36% [95% CI: 15–65]), one exclusively by EBD search (9% [95% CI: 1–38]), and six exclusively by CTR search (55% [95% CI: 28–79])). Also, we identified 42 eligible ongoing RCTs: 16 by both sources (38% [95% CI: 25–53]) and 26 exclusively by CTR search (62% [95% CI: 47–75]). Lastly, we identified four RCTs of unknown status by both sources. CTR searches identify a greater number of completed RCTs than EBD searches. Both searches missed some included RCTs. Based on our case study, researchers (eg, information specialists, systematic reviewers) aiming to identify all available RCTs should continue to search both sources. Once the barriers to performing CTR searches alone are targeted, CTR searches may be a suitable alternative. [Display omitted]

• Publisher: Elsevier Inc,Elsevier Limited
• Subject: Bias / Bibliographic data bases / Bibliographies / Case studies / Clinical trial register search / Clinical trial registry / Clinical trials / Data collection / Databases, Bibliographic - statistics & numerical data / Handbooks / Humans / Information retrieval / Information Storage and Retrieval - methods / Information Storage and Retrieval - statistics & numerical data / Intervention / Kidney diseases / Randomized clinical trials / Randomized controlled trials / Randomized Controlled Trials as Topic - methods / Randomized Controlled Trials as Topic - standards / Randomized Controlled Trials as Topic - statistics & numerical data / Registers / Registration / Registries - statistics & numerical data / Searching / Systematic review / Systematic Reviews as Topic - methods