Infrequent and incomplete registration of test accuracy studies: analysis of recent study reports

To identify the proportion of articles reporting on test accuracy for which the corresponding study had been registered.

Analysis of a consecutive sample of published study reports.

PubMed was searched for publications in journals with an impact factor of 5 or higher in May and June 2012. Articles were included if they reported on original studies evaluating the accuracy of one or more diagnostic or prognostic tests or markers against a clinical reference standard in humans.

Primary outcome was registration of the reported test accuracy study. We additionally explored study characteristics associated with registration.

We found 1941 references; 351 study reports fulfilled the inclusion criteria, of which 52 studies (15%) had been registered. Of these, 27 (52%) provided a registration number in the publication, and 12 (23%) provided a reference to the publication in the registry. Registration rates were similar for studies on diagnostic versus those on prognostic tests, and among studies on imaging tests versus those on laboratory techniques. Studies reporting some form of industry involvement were more often registered (33%) than studies reporting another source of funding (11%), and studies without a (reported) source of (external) funding (9%; p<0.001). Of the registered studies, 8 (15%) had been registered after completion, 14 were registered before initiation (27%) and 30 (58%) between initiation and completion. Only 16 (31%; 5% of the total sample) had registered the published primary outcome measures before completion.

Few test accuracy studies published in higher impact journals are registered. Only 1 in 22 of such studies register their primary outcomes before study completion. Owing to the reasons for registering studies that investigate the cause-and-effect relationship between health-related interventions and health outcomes also apply to test accuracy studies, prospective study registration of these studies should be further promoted among investigators and journal editors.