Warfarin treatment quality is consistently high in both anticoagulation clinics and primary care setting in Sweden

Background: Warfarin treatment in Sweden holds a high standard with time in therapeutic range (TTR) over 75%. Internationally, specialized anticoagulation clinics (ACC) have shown higher TTR compared to primary health care centres (PHCC).

Objectives: To compare warfarin treatment quality in Sweden for ACC versus PHCC, thereby clarifying whether centralization is for the better.

Patients/methods: In total 77.058 patients corresponding to 217.058 treatment years with warfarin in the Swedish national quality register AuriculA from 1. Jan 2006 to 31. Dec 2011. Information regarding TTR was calculated from AuriculA, while patient characteristics and complications were retrieved from the Swedish National Patient Register.

Results: Of the 100.554 treatment periods examined, 78.7% were monitored at ACC. Mean TTR for INR 2-3 for all patients irrespective of intended target range was 76.5% with an annual risk of bleeding or thrombotic events of 2.24% and 2.66%, respectively. TTR was significantly higher in PHCC compared to ACC (79.6% vs. 75.7%, p<0.001), with no significant difference in overall risk of complications. Treatment periods for atrial fibrillation, except intended direct current conversion, showed similar results between ACC and PHCC without significant difference in annual risk of bleeding (2.50% vs. 2.51%) or thrombosis (3.09% vs. 3.16%). After propensity score matching there was still no significant difference in complication risk found.

Conclusions: Warfarin treatment quality is consistently high in both ACC and PHCC when monitored through AuriculA in Sweden, both measured as TTR and as risk of complications. In this setting, centralized warfarin monitoring is not likely to improve the results.