Searching practices and inclusion of unpublished studies in systematic reviews of diagnostic accuracy

Daniël A Korevaar (1) , Jean‐paul Salameh (2) , Yasaman Vali (3) , Jérémie F Cohen (4, 5) , Matthew D F Mcinnes (6) , René Spijker (7) , Patrick M Bossuyt (3)

1 Department of Respiratory Medicine, Amsterdam University Medical Centres, University of Amsterdam, The Netherlands
2 Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
3 Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Amsterdam University Medical Centres, University of Amsterdam, Amsterdam, the Netherlands
4 Department of General Pediatrics and Pediatric Infectious Diseases, Necker- Enfants Malades Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
5 CRESS (U1153 / UMR_A_1125 / UMR_S_1153) - Centre de Recherche Épidémiologie et Statistique Sorbonne Paris Cité
6 Department of Radiology, University of Ottawa, Ottawa, Canada
7 Cochrane Netherlands, Julius Center for Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht University, The Netherlands

Introduction: Many diagnostic accuracy studies are never reported in full in a peer-reviewed journal. Searching for unpublished studies may avoid bias due to selective publication, enrich the power of systematic reviews, and thereby help to reduce research waste. We assessed searching practices among recent systematic reviews of diagnostic accuracy. Methods: We extracted data from 100 non-Cochrane systematic reviews of diagnostic accuracy indexed in MEDLINE and published between October 2017 and January 2018 and from all 100 Cochrane systematic reviews of diag- nostic accuracy published by December 2018, irrespective of whether meta- analysis had been performed. Results: Non-Cochrane and Cochrane reviews searched a median of 4 (IQR 3-5) and 6 (IQR 5-9) databases, respectively; most often MEDLINE/PubMed (n = 100 and n = 100) and EMBASE (n = 81 and n = 100). Additional efforts to identify studies beyond searching bibliographic databases were performed in 76 and 98 reviews, most often through screening reference lists (n = 71 and n = 96), review/guideline articles (n = 18 and n = 52), or citing articles (n = 3 and n = 42). Specific sources of unpublished studies were searched in 22 and 68 reviews, for example, conference proceedings (n = 4 and n = 18), databases only containing conference abstracts (n = 2 and n = 33), or trial registries (n = 12 and n = 39). At least one unpublished study was included in 17 and 23 reviews. Overall, 39 of 2082 studies (1.9%) included in non-Cochrane reviews were unpublished, and 64 of 2780 studies (2.3%) in Cochrane reviews, most often conference abstracts (97/103). Conclusion: Searching practices vary considerably across systematic reviews of diagnostic accuracy. Unpublished studies are a minimal fraction of the evi- dence included in recent reviews.

Domains: Life Sciences [q-bio]; Life Sciences [q-bio]; Santé publique et épidémiologie; Statistics [stat]

Daniël A Korevaar, Jean‐paul Salameh, Yasaman Vali, Jérémie F Cohen, Matthew D F Mcinnes, et al.. Searching practices and inclusion of unpublished studies in systematic reviews of diagnostic accuracy. Research Synthesis Methods, 2020, 11 (3), pp.343-353. ⟨10.1002/jrsm.1389⟩. ⟨hal-03946669⟩