TY - JOUR
T1 - Impact of searching clinical trials registers in systematic reviews of pharmaceutical and non-pharmaceutical interventions
T2 - Reanalysis of meta-analyses
AU - Alqaidoom, Zainab
AU - Nguyen, Phi-Yen
AU - Awadh, Maryam
AU - Page, Matthew J.
N1 - Funding Information:
Australian Research Council, Grant/Award Number: DE200101618 Funding information
Funding Information:
Matthew J. Page is supported by an Australian Research Council Discovery Early Career Researcher Award (DE200101618). The funders had no role in the study design, decision to publish, or preparation of the manuscript.
Publisher Copyright:
© 2022 The Authors. Research Synthesis Methods published by John Wiley & Sons Ltd.
PY - 2023/1
Y1 - 2023/1
N2 - Systematic reviewers are advised to search trials registers to minimise risk of reporting biases. However, there has been little research on the impact of searching trials registers on the results of meta-analyses. We aimed to evaluate the impact of searching clinical trials registers for systematic reviews of pharmaceutical or non-pharmaceutical interventions. We searched PubMed, Scopus, Science Citation Index and Social Sciences Citation Index, and Education Collection for systematic reviews with meta-analyses indexed from 2 November to 2 December 2020. A random sample of systematic reviews was initially drawn, and for reviews which considered randomised trials eligible for inclusion, which had not searched a trials register, we searched ClinicalTrials.gov, EudraCT, ANZCTR, and the WHO ICTRP search portal for eligible trials. We compared meta-analytic effect estimates before and after including results from additional trials identified. We found additional trials for 63% (63/101) of eligible reviews; however, trials with results that could contribute to a meta-analysis were identified for only 20% (20/101) of the reviews. On average, there was no difference in the meta-analytic effect estimates before versus after adding the new trials. In summary, searching clinical trial registers led to identification of additional trials for many reviews; however, very few trials had results available for inclusion in meta-analyses. Including results from the new trials led to no change in the meta-analytic estimates, on average. Trials registers would be even more valuable to systematic reviewers if more trialists made use of them (i.e., registered their trials and posted results in a timely manner).
AB - Systematic reviewers are advised to search trials registers to minimise risk of reporting biases. However, there has been little research on the impact of searching trials registers on the results of meta-analyses. We aimed to evaluate the impact of searching clinical trials registers for systematic reviews of pharmaceutical or non-pharmaceutical interventions. We searched PubMed, Scopus, Science Citation Index and Social Sciences Citation Index, and Education Collection for systematic reviews with meta-analyses indexed from 2 November to 2 December 2020. A random sample of systematic reviews was initially drawn, and for reviews which considered randomised trials eligible for inclusion, which had not searched a trials register, we searched ClinicalTrials.gov, EudraCT, ANZCTR, and the WHO ICTRP search portal for eligible trials. We compared meta-analytic effect estimates before and after including results from additional trials identified. We found additional trials for 63% (63/101) of eligible reviews; however, trials with results that could contribute to a meta-analysis were identified for only 20% (20/101) of the reviews. On average, there was no difference in the meta-analytic effect estimates before versus after adding the new trials. In summary, searching clinical trial registers led to identification of additional trials for many reviews; however, very few trials had results available for inclusion in meta-analyses. Including results from the new trials led to no change in the meta-analytic estimates, on average. Trials registers would be even more valuable to systematic reviewers if more trialists made use of them (i.e., registered their trials and posted results in a timely manner).
KW - meta-analysis
KW - publication bias
KW - systematic review
KW - trial registration
UR - http://www.scopus.com/inward/record.url?scp=85135034999&partnerID=8YFLogxK
U2 - 10.1002/jrsm.1583
DO - 10.1002/jrsm.1583
M3 - Article
C2 - 35796034
AN - SCOPUS:85135034999
SN - 1759-2879
VL - 14
SP - 52
EP - 67
JO - Research Synthesis Methods
JF - Research Synthesis Methods
IS - 1
ER -