Development of a matrix of cost domains in economic evaluation of rheumatoid arthritis

The aim of our study was to comprehensively review and critically appraise the cost domains used in economic evaluations of the rheumatic diseases and to use this information to propose standardization of cost domains. The literature search identified 210 abstracts, 32 of which included original cost data. The listed cost categories were grouped into 3 major areas: (direct) health care costs, other (direct) disease related costs, and productivity costs (indirect costs). The number of individual cost categories was reduced by considering the following criteria: (1) inclusion of all relevant cost domains; (2) avoidance of double counting; (3) summarizing of related categories under one representative heading; (4) feasibility of level of aggregation. After adjustment for synonymous labeling, 38 cost categories remained. The subsequent development of a classification scheme of cost categories led to a set of 19 separate cost domains including 7 outpatient, 3 inpatient, 6 other disease related, and 3 productivity cost domains. This literature review indicates that cost assessment in economic evaluations in rheumatoid arthritis lacks standardization. A preliminary scheme to categorize cost assessment in rheumatic conditions is presented. The adoption of standards for economic evaluation would greatly facilitate national and international comparisons.