Definition, harms, and prevention of redundant systematic reviews

Abstract

Background Along with other types of research, it has been stated that the extent of redundancy in systematic reviews has reached epidemic proportions. However, it was also emphasized that not all duplication is bad, that replication in research is essential, and that it can help discover unfortunate behaviors of scientists. Thus, the question is how to define a redundant systematic review, the harmful consequences of such reviews, and what we could do to prevent the unnecessary amount of this redundancy. Main body There is no consensus definition of a redundant systematic review. Also, it needs to be defined what amount of overlap between systematic reviews is acceptable and not considered a redundancy. One needs to be aware that it is possible that the authors did not intend to create a redundant systematic review. A new review on an existing topic, which is not an update, is likely justified only when it can be shown that the previous review was inadequate, for example, due to suboptimal methodology. Redundant meta-analyses could have scientific, ethical, and economic questions for researchers and publishers, and thus, they should be avoided, if possible. Potential solutions for preventing redundant reviews include the following: (1) mandatory prospective registration of systematic reviews; (2) editors and peer reviewers rejecting duplicate/redundant and inadequate reviews; (3) modifying the reporting checklists for systematic reviews; (4) developing methods for evidence-based research (EBR) monitoring; (5) defining systematic reviews; (6) defining the conclusiveness of systematic reviews; (7) exploring interventions for the adoption of methodological advances; (8) killing off zombie reviews (i.e., abandoned registered reviews); (9) better prevention of duplicate reviews at the point of registration; (10) developing living systematic reviews; and (11) education of researchers. Conclusions Disproportionate redundancy of the same or very similar systematic reviews can lead to scientific, ethical, economic, and societal harms. While it is not realistic to expect that the creation of redundant systematic reviews can be completely prevented, some preventive measures could be tested and implemented to try to reduce the problem. Further methodological research and development in this field will be welcome.

A timely review for systematic reviews

“…An additional concern the authors identify is that of redundant reviews, that is, reviews that overlap and may be deemed as wasteful and unnecessary 1 . This topic has been discussed repeatedly in the literature, most recently by Puljak and Lund 3 . It is a critical issue that we will explore further and discuss in a future editorial.…”

Reviews and Reviewing: Approaches to Research Synthesis. An Annual Review of Information Science and Technology (ARIST) paper

“…These standards encompass initiating a systematic review; finding and assessing individual studies; synthesizing the body of evidence; and reporting systematic reviews. Puljak and Lund (2023) identify a number of approaches to reduce the proliferation of redundant systematic reviews. Kolaski et al (2023) have developed a concise guide to best practices for evidence synthesis to improve the reliability of systematic reviews.…”

Fast clinical trial identification using fuzzy-search elastic searches: retrospective validation with high-quality Cochrane benchmark

“…A Cochrane systematic review typically requires one to two years to complete. This time and effort limits the speed and flexibility that can advance evidence-based medicine, resulting in many meta-analyses and systematic reviews on the same topic that are sometimes redundant (Chapelle et al, 2021; Puljak et al, 2023).…”