A new taxonomy was developed for overlap across 'overviews of systematic reviews': A meta‐research study of research waste

Abstract

BackgroundMultiple 'overviews of reviews' conducted on the same topic ("overlapping overviews") represent a waste of research resources and can confuse clinicians making decisions amongst competing treatments. We aimed to assess the frequency and characteristics of overlapping overviews. MethodsMEDLINE, Epistemonikos and Cochrane Database of Systematic Reviews were searched for overviews that: synthesised reviews of health interventions and conducted systematic searches. Overlap was de ned as: duplication of PICO eligibility criteria, and not reported as an update nor a replication. We categorized overview topics according to 22 WHO ICD-10 medical classi cations, overviews as broad or narrow in scope, and overlap as identical, nearly identical, partial, or subsumed. Subsummation was de ned as when broad overviews subsumed the populations, interventions and at least one outcome of another overview. ResultsOf 541 overviews included, 169 (31%) overlapped across similar PICO, fell within 13 WHO ICD-10 medical classi cations, and 62 topics. 148/169 (88%) overlapping overviews were broad in scope. Fifteen overviews were classi ed as having nearly identical overlap (9%); 123 partial overlap (73%), and 31 subsumed (18%) others. ConclusionsOne third of overviews overlapped in content and a majority covered broad topic areas. A multiplicity of overviews on the same topic adds to the ongoing waste of research resources, time and effort across medical disciplines. Authors of overviews can use this study and the sample of overviews to identify gaps in the evidence for future analysis, and topics that are already studied which do not need to be duplicated. HighlightsThis is the rst study to examine overlap across a sample of overviews of reviews.Of 541 overviews published from 2000 to 2018, 169 (31%) were considered overlapping in topic with one or more overviews.

Guidelines, guidelines and more guidelines for haemorrhoid treatment: A review to sort the wheat from the chaff

“…The problem of redundant and overlapping guidelines is similar to that observed in systematic reviews, where variable methodological quality and coverage result in different estimates of effect sizes for the same question [44]. There is often overlap between the scopes of different systematic reviews, without them being coterminous, because some cover broad and other narrow topic areas [45]. In our review even guidelines that were restricted to surgery had different patterns of attention, while other guidelines also covered alternative management strategies.…”

“…Like systematic review authors [45], guideline committees should acknowledge the existence of previous or ongoing work and justify the need for new guidance. Whilst guidelines have the potential to underpin safe practice and provide safeguards for both patients and clinicians [47], expert and consensus approaches can go beyond high quality evidence, sometimes resulting in inappropriate recommendations [48].…”

Definition, harms, and prevention of redundant systematic reviews

“…For example, in 2021, Lunny et al proposed a taxonomy for overlapping overviews of systematic reviews addressing health interventions [ 9 ]. The overlap was defined as a duplication of PICO (patients, interventions, comparators, outcomes) eligibility criteria and was not reported as an update or a replication.…”

“…The overlap was defined as a duplication of PICO (patients, interventions, comparators, outcomes) eligibility criteria and was not reported as an update or a replication. The overlapping overviews were classified into four categories — identical, nearly identical, partial, or subsumed [ 9 ]. Definitions for all four categories were proposed.…”

Umbrella reviews: a useful study design in need of standardisation

“…The Cochrane Handbook for Systematic Reviews of Interventions and Joanna Briggs Institute Manual provide recommendations for umbrella reviews of interventions,2728 but additional resources are needed to accommodate different scenarios. Together, these efforts could help standardise approaches, minimise the need for authors to make subjective decisions, and ultimately reduce the number of overlapping umbrella reviews that are conducted using different methodological approaches 29…”