Supplementary Appendix 1 and Supplementary Appendix 2

Prevalence and incidence are fundamental metrics with numerous applications in epidemiology. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guideline lacks specific items for reporting studies of disease prevalence or incidence. We developed the STROBE extension ‘Enhanced Prevalence and Incidence Criteria’ (EPIC) in accordance with established methods for reporting guideline development to address this gap. We generated an initial list of reporting items and conducted the first Delphi survey with experts on typhoid and other salmonelloses, the disease area that motivated STROBE EPIC. We convened a face-to-face consensus meeting to confirm the need for a STROBE extension and to generate an early version of the checklist. We conducted two further Delphi surveys, first extending to experts on other infectious diseases, and then to non-communicable diseases and injuries. Finally, experts piloted the checklist on relevant manuscripts to critically assess if it was clear, concise, complete, and free of errors. An executive group curated the checklist after every survey round. The STROBE EPIC checklist comprises 47 items in the domains of: title (one item), abstract (two items), introduction (one item), methods (25 items), results (six items), discussion (seven items), and other information (five items). STROBE EPIC items address reporting of surveillance design, adjustment factors for under-reporting or under-diagnosis, denominator population estimation, case ascertainment methods, factors producing artefactual changes to observed disease prevalence or incidence, limitations of incomplete surveillance coverage, generalisability of short-duration studies, and data availability. We anticipate the STROBE EPIC extension will be used by researchers, authors, modellers, burden of disease researchers, peer-reviewers, and journal editors, to optimise the presentation of epidemiologic evidence to support diverse health policy decisions.

Funding: The Bill & Melinda Gates Foundation.