Exploring transparent reporting and data availability in systematic reviews to identify subgroup evidence: imaging for suspected hepatocellular carcinoma in the non-cirrhotic liver.

We aim to illustrate the role of complete and transparent reporting coupled with access to data sourced from published systematic reviews, especially assisting in the identification of evidence for subgroups within the context of a rare disease. To accomplish this principle, we provide a real-world example encountered during the revision of the Dutch clinical practice guideline for hepatocellular carcinoma. Specifically, we retrieved insights from two Cochrane reviews to identify direct evidence concerning the diagnostic test accuracy of computed tomography and magnetic resonance imaging for detecting hepatocellular carcinomas in suspected patients without liver cirrhosis. Through reusing the Cochrane review authors' efforts already undertaken in their exhaustive literature search and selection, we successfully identified relevant direct evidence for this subgroup of suspected patients without cirrhosis and performed an evidence synthesis within the constraints of limited resources for the guideline revision. This approach holds the potential for replication in other subgroups in the context of rare diseases, contingent on the transparent and complete reporting of systematic reviews, as well as the availability and accessibility of their extracted data. Consequently, we underscore the importance of adhering to established reporting guidelines for systematic reviews, while simultaneously advocating for increased availability and accessibility to data. Such practices would not only increase the transparency and reproducibility of systematic reviews but could also increase reusability of their data. In turn, the increased reusability could result in reduced resource utilization in other sectors such as the guideline developing community as we show in our example.