Effects of double data extraction on errors in evidence synthesis: a crossover, multicenter, investigator-blinded, randomized controlled trial

Objectives The objective was to investigate the role of duet extraction in reducing data errors in evidence synthesis for pharmaceutical and non-pharmaceutical interventions. Design Randomized controlled trial. Setting University teaching center and hospital evidence-based medicine center. Participants Eligible 100 participants were 2nd year or above post-graduate students (e.g., masters, doctoral program), who were randomly (1:1) assigned for data extraction tasks of either 10 RCTs of pharmaceutical interventions or 10 of non-pharmaceutical interventions, followed by a cross-over pattern and a further double-checking process. Intervention The intervention of this trial was double-checking process for data extraction. Primary and secondary outcome measures The primary outcome was the error rates for RCTs in the pharmaceutical versus non-pharmaceutical intervention group, in terms of both study level and cell level (2 by 2 table). The secondary outcome was the absolute difference in the error rates before and after the double-checking process for both the pharmaceutical and non-pharmaceutical intervention groups, again, in terms of both study level and cell level (2 by 2 table). Results The error rates in RCTs of pharmaceutical and non-pharmaceutical groups were 64.65% and 59.90%, with an absolute difference of 4.75% and an odds ratio (OR) of 1.29 (95%CI: 1.06 to 1.57, P = 0.01) when measured at the study level. After double-checking, the error rates decreased to 44.88% and 39.54%, and the difference between the two groups remained at 5.34%, with the OR of 1.27 (95%CI: 1.1 to 1.46; P < 0.01). Similar results were observed when measured at the cell level. Conclusion Double-checking reduced data extraction errors, but the error rate still remained high after the process. Further evidence synthesis research may consider to use triple data extraction to minimize potential errors. Trial registration number Chinese Clinical Trial Registry Center (Identifier: ChiCTR2200062206) ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial ChiCTR2200062206 ### Clinical Protocols ### Funding Statement This work was supported by the National Natural Science Foundation of China (72204003), the Academic Discipline Development (0301001882) from Anhui Medical University and the program grant #NPRP-BSRA01-0406-210030 from the Qatar National Research Fund (a member of Qatar Foundation). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This trial was approved by the Institutional Review Board at Anhui Medical University (No. 83220405), and has been registered with the Chinese Clinical Trial Registry Center (Identifier: ChiCTR2200062206). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data will be shared to the public after the publication of the trial within 3 months.