Published online Oct 21, 2017. doi: 10.3748/wjg.v23.i39.7198
Peer-review started: August 29, 2017
First decision: September 13, 2017
Revised: September 15, 2017
Accepted: September 26, 2017
Article in press: September 26, 2017
Published online: October 21, 2017
Processing time: 53 Days and 19.4 Hours
Duplicate publication can introduce significant bias into a meta-analysis if studies are inadvertently included more than once. Many studies are published in more than one journal to maximize readership and impact of the study findings. Inclusion of multiple publications of the same study within a meta-analysis affords inappropriate weight to the duplicated data if reports of the same study are not linked together. As studies which have positive findings are more likely to be published in multiple journals this leads to a potential overestimate of the benefits of an intervention. Recent advances in immunosuppression strategies following liver transplantation have led to many studies investigating immunosuppressive regimes including immunosuppression monotherapy. In this letter we focus on a recently published meta-analysis by Lan et al investigating studies assessing immunosuppression monotherapy for liver transplantation. The authors claim to have identified fourteen separate randomised studies investigating immunosuppression monotherapy. Seven of the references appear to relate to only three studies which have been subject to duplicate publication. Several similarities can be identified in each of the duplicate publications including similar authorship, identical immunosuppression regimes, identical dates of enrolment and citation of the original publication in the subsequent manuscripts. We discuss the evidence of the duplicate publication inclusion in the meta-analysis.
Core tip: The purpose of this letter to the editor is to comment on the potential inclusion of duplicate publications within the meta-analysis titled: “Efficacy of immunosuppression monotherapy after liver transplantation: A meta-analysis”.