Oral anticoagulant therapy (OAT) is used to prevent thrombosis in patients with atrial fibrillation (AF), venous thrombosis and prosthetic heart valves. The numbers of patients on OAT is steadily increasing worldwide. Although new drugs are being introduced, vitamin K antagonists (VKA) still predominate. The introduction of new therapies emphasizes the need to discern the best practice for patients remaining on warfarin treatment. In Sweden, the number of VKA-treated patients is approaching 200,000, almost 2% of the population, and the treatment is almost exclusively warfarin.
Good therapeutic control of VKA treatment, with regular prothrombin time (PT) tests reported as International Normalized Ratio (INR) within intended therapeutic range (TR) is imperative for minimizing adverse events (bleeding and/or thrombosis) [1–4].
A comprehensive study concluded that anticoagulation control in community-based patients with AF in the USA was similar to participants in clinical trials . Prospective data on VKA management are limited, but most retrospective studies favor specialized anticoagulation clinics (ACCs) over “usual care” [1, 4, 6]. However, these results cannot be automatically extrapolated to Sweden, which has a high standard of VKA management and primary health care. This is exemplified by the recent Swedish national quality registry—Auricula—study, which showed that the quality of anticoagulation treatment in Swedish centers is high, with a mean TTR of 76.2% .
A previous Swedish study found no differences in bleeding complications between Swedish primary health care centers (PHCC) and ACC .
Although the general trend in Sweden is toward more centralized (ACC) management of VKA treatment, some counties prefer to use the patient’s PHCC instead. There is, theoretically, a third option, with patients testing themselves with or without self-management of dosing. However, this group is very small in Sweden, estimated at fewer than 1,000 patients.
Most study data about the therapeutic control of VKA treatment originates from centralized ACCs with computer registers for treatment data, leaving the more scattered and hard-to-access PHCC data relatively unexplored. At the time this study was conducted, both regimes, ACC and PHCC VKA management, coexisted in our region. Both settings offered similar services, including initiation/induction and continued treatment.
Delivery of care for patients requiring warfarin therapy can be organized according to completely different principles. The different settings should therefore be characterized and compared, preferably with actual “real-life” populations not subjected to interventional studies where the patient material is usually selected, before deciding which organization is best suited to satisfy local health care challenges. The introduction of new therapies, with an obvious impact on future management of anticoagulation therapy, further emphasizes the need to conduct studies to determine best practice for warfarin management.
The Rosendaal method , commonly used for Time in Therapeutic Range (TTR) calculations, is very cumbersome to perform in non-computerized settings. A cross-sectional method is more feasible in such a setting and was therefore chosen for this particular study.
The purpose of the present observational study was to perform a non-selective, snapshot cross-section comparison of the main patient characteristics and therapeutic control in the two different settings (PHCC and ACC) used for managing VKA treatment in a large population in our region. This also includes an investigation of potential differences between these two settings with respect to the proportion of PT-INR results within TR overall, and between men and women.