Patient assessment using standardized bone mineral density values and a national reference database: implementing uniform thresholds for the reimbursement of osteoporosis treatments in Belgium

Dual-energy X-ray absorptiometry (DXA) devices from the three main manufacturers provide different bone mineral density (BMD) values, due in part to technical differences in the algorithms for bone mineral content (BMC) and area measurements and in part to the use of different manufacturer-derived reference databases. As a result, significant differences exist between Hologic, Lunar and Norland systems in the reported young normal standard deviation scores or T-scores. In a number of European countries, including Belgium, a T-score below −2.5 is one of the key criteria for reimbursement of osteoporosis treatments. This paper addresses the first attempt to implement a nationwide, uniform expression of BMD in patients, in order to harmonize drug reimbursement. To this end, measures were taken to implement a uniform expression of BMD in Belgian patients, by converting each manufacturer's absolute BMD to standardized BMD (sBMD) values and by establishing a single national reference range.