Systematic overview finds variation in approaches to investigating and reporting on sources of heterogeneity in systematic reviews of diagnostic studies

To examine how authors explore and report on sources of heterogeneity in systematic reviews of diagnostic accuracy studies. 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. 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 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