{"doi":"10.1136/bmj.f4501","title":"Overlapping meta-analyses on the same topic: survey of published studies","abstract":"<h4>Objective</h4>To assess how common it is to have multiple overlapping meta-analyses of randomized trials published on the same topic.<h4>Design</h4>Survey of published meta-analyses.<h4>Data sources</h4>PubMed.<h4>Study selection and methods</h4>Meta-analyses published in 2010 were identified, and 5% of them were randomly selected. We further selected those that included randomized trials and examined effectiveness of any medical intervention. For eligible meta-analyses, we searched for other meta-analyses on the same topic (covering the same comparisons, indications/settings, and outcomes or overlapping subsets of them) published until February 2013.<h4>Results</h4>Of 73 eligible meta-analyses published in 2010, 49 (67%) had at least one other overlapping meta-analysis (median two meta-analyses per topic, interquartile range 1-4, maximum 13). In 17 topics at least one author was involved in at least two of the overlapping meta-analyses. No characteristics of the index meta-analyses were associated with the potential for overlapping meta-analyses. Among pairs of overlapping meta-analyses in 20 randomly selected topics, 13 of the more recent meta-analyses did not include any additional outcomes. In three of the four topics with eight or more published meta-analyses, many meta-analyses examined only a subset of the eligible interventions or indications/settings covered by the index meta-analysis. Conversely, for statins in the prevention of atrial fibrillation after cardiac surgery, 11 meta-analyses were published with similar eligibility criteria for interventions and setting: there was still variability on which studies were included, but the results were always similar or even identical across meta-analyses.<h4>Conclusions</h4>While some independent replication of meta-analyses by different teams is possibly useful, the overall picture suggests that there is a waste of efforts with many topics covered by multiple overlapping meta-analyses.","journal":"BMJ","year":2013,"id":3287,"datarank":0.8341022446523293,"base_score":5.560681631015528,"endowment":5.560681631015528,"self_citation_contribution":0.8341022446523293,"citation_network_contribution":0.0,"self_endowment_contribution":0.8341022446523293,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":259,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.2567,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2013-07-19","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":3375,"name":"Konstantinos C. Siontis","orcid":"0000-0002-6658-0971","position":3,"is_corresponding":false},{"id":35255,"name":"Tina Hernandez‐Boussard","orcid":"0000-0001-6553-3455","position":4,"is_corresponding":false},{"id":148,"name":"John P. A. Ioannidis","orcid":"0000-0003-3118-6859","position":5,"is_corresponding":false},{"id":37698,"name":"Konstantinos CM Siontis","orcid":null,"position":0,"is_corresponding":true}],"reference_count":46,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-03-01T18:20:47.508186Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}