A systematic survey identified methodological issues in studies estimating anchor-based minimal important differences in patient-reported outcomes

To systematically survey the literature addressing the reporting of studies estimating anchor-based minimal important differences (MIDs) and choice of optimal MIDs.We searched Medline, Embase and PsycINFO from 1987 to March 2020. Teams of two reviewers independently identified eligible publications and extracted quotations addressing relevant issues for reporting and/or selecting anchor-based MIDs. Using a coding list, we assigned the same code to quotations capturing similar or related issues. For each code, we generated an 'item', i.e., a specific phrase or sentence capturing the underlying concept. When multiple concepts existed under a single code, the team created multiple items for that code. We clustered codes addressing a broader methodological issue into a 'category' and classified items as relevant for reporting, relevant for selecting an anchor-based MID, or both.We identified 136 eligible publications that provided 6 categories (MID definition, anchors, patient-reported outcome measures, generalizability and statistics) and 24 codes. These codes contained 34 items related to reporting MID studies, of which 29 were also related to selecting MIDs.The systematic survey identified items related to reporting of anchor-based MID studies and selecting optimal MIDs. These provide a conceptual framework to inform the design of studies related to MIDs, and a basis for developing a reporting standard and a selection approach for MIDs.