International Variation in the Usage of Medicines: A Review of the Literature.

This article describes a review of the published and grey literature on international variation in the use of medicines in six areas (osteoporosis, atypical anti-psychotics, dementia, rheumatoid arthritis, cardiovascular disease/lipid-regulating drugs (statins), and hepatitis C). We identify three broad groups of determinants of international variation in medicines use: (1) Macro- or system level factors: Differences in reimbursement policies, and the role of health technology assessment, were highlighted as a likely driving force of international variation in almost all areas of medicines use reviewed. A related aspect is patient co-payment, which is likely to play an important role in the United States in particular. The extent to which cost-sharing policies impact on overall use of medicines in international comparison remains unclear. (2) Service organisation and delivery: Differences in access to specialists are a likely driver of international variation in areas such as atypical anti-psychotics, dementia, and rheumatic arthritis, with for example access to and availability of relevant specialists identified as acting as a crucial bottleneck for accessing treatment for dementia and rheumatoid arthritis. (3) Clinical practice: Studies highlighted the role of variation in the use and ascertainment methods for mental disorders; differences in the use of clinical or practice guidelines; differences in prescribing patterns; and reluctance among clinicians in some countries to take up newer medicines. Each of these factors is likely to play a role in explaining international variation in medicines use, but their relative importance will vary depending on the disease area in question and the system context.