A consensus-based checklist for the critical appraisal of cost-of-illness (COI) studies.

To develop a consensus-based checklist that can be used as a minimum standard to appraise the comprehensiveness, transparency and consistency of cost-of-illness (COI) studies. This is important when, for instance, reviewing and assessing COI studies as part of a systematic review or when building an economic model. The development process of the consensus-based checklist involved six steps: (i) a scoping review, (ii) an assessment and comparison of the different checklists and their questions, (iii) the development of a (preliminary) checklist, (iv) expert interviews, (v) the finalization of the checklist, and (vi) the development of guidance statements explaining each question. The result was a consensus-based checklist for the critical appraisal of COI studies, comprising seventeen main questions (and some additional subquestions) across three domains: (i) study characteristics; (ii) methodology and cost analysis; and (iii) results and reporting. Guidance statements were developed describing the purpose and meaning behind each question and listing examples of best practice. The following answer categories were suggested to be applied when answering the questions in the checklist: The consensus-based checklist for COI studies is a first step toward standardizing the critical appraisal of COI studies and is one that could be considered a minimum standard. The checklist can help to improve comprehensiveness, transparency and consistency in COI studies, to address heterogeneity, and to enable better comparability of methodological approaches across international studies.