title: Systematic overview finds variation in approaches to investigating and reporting on sources of heterogeneity in systematic reviews of diagnostic studies.
abstract: OBJECTIVE
  To examine how authors explore and report on sources of heterogeneity in systematic reviews of diagnostic accuracy studies.
  
  
  METHODS
  A cohort of systematic reviews of diagnostic tests was systematically identified. Data were extracted on whether an exploration of the sources of heterogeneity was undertaken, how this was done, the number and type of potential sources explored, and how results and conclusions were reported.
  
  
  RESULTS
  Of the 65 systematic reviews, 12 did not perform a meta-analysis and eight of these gave heterogeneity between studies as a reason. Of the 53 reviews containing a meta-analysis, 40 explored potential sources of heterogeneity in a formal manner and 27 identified at least one source of heterogeneity. The reviews not investigating heterogeneity were smaller than those that did (median [interquartile range {IQR}], 8 [5-15] vs. 14 [11-19] primary studies). Twelve reviews performed a sensitivity analysis, 25 stratified analyses, and 19 metaregression. Many sources of heterogeneity were explored compared with the number of primary studies in a meta-analysis (median ratio, 1:5). Review authors placed importance on the exploration of sources of heterogeneity; 37 mentioned the exploration or the findings thereof in the abstract or conclusion of the main text.results
  
  
  CONCLUSIONS
  Methods for investigating sources of heterogeneity varied widely between reviews. Based on our findings of the review, we made suggestions on what to consider and report on when exploring sources of heterogeneity in systematic reviews of diagnostic studies.
authors: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands. Electronic address: c.naaktgeboren@umcutrecht.nl.
authors: Christiana A
authors: CA
authors: Naaktgeboren
authors: Dutch Cochrane Centre, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands; Department of Clinical Epidemiology, Biostatistics and Bioinformatics (KEBB), Academic Medical Centre (AMC), University of Amsterdam (UvA), Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: Wynanda A
authors: WA
authors: van Enst
authors: Department of Clinical Epidemiology, Biostatistics and Bioinformatics (KEBB), Academic Medical Centre (AMC), University of Amsterdam (UvA), Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; Department of Interdisciplinary Health, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 19063, Francie van Zijl Drive, TYGERBERG 7505, South Africa.
authors: Eleanor A
authors: EA
authors: Ochodo
authors: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands.
authors: Joris A H
authors: JA
authors: de Groot
authors: Dutch Cochrane Centre, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands; Department of Clinical Epidemiology, Biostatistics and Bioinformatics (KEBB), Academic Medical Centre (AMC), University of Amsterdam (UvA), Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: Lotty
authors: L
authors: Hooft
authors: Dutch Cochrane Centre, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands; Department of Clinical Epidemiology, Biostatistics and Bioinformatics (KEBB), Academic Medical Centre (AMC), University of Amsterdam (UvA), Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: Mariska M
authors: MM
authors: Leeflang
authors: Department of Clinical Epidemiology, Biostatistics and Bioinformatics (KEBB), Academic Medical Centre (AMC), University of Amsterdam (UvA), Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: Patrick M
authors: PM
authors: Bossuyt
authors: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands.
authors: Karel G M
authors: KG
authors: Moons
authors: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands.
authors: Johannes B
authors: JB
authors: Reitsma
mesh_terms: D003955:Diagnostic Tests, Routine / Q000379:methods / Q000592:standards* / Q000706:statistics & numerical data; D006801:Humans; D012107:Research Design
keywords: Bias (epidemiology); Data interpretation; Diagnostic techniques and procedures/standards; Meta-analysis; Sensitivity and specificity; Statistical