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Warfarin treatment quality is consistently high in both anticoagulation clinics and primary care setting in Sweden
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine. (Sundsvall Research Unit, Umeå University)
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine. (Sundsvall Research Unit, Umeå University)
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2015 (English)In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 136, no 2, 216-220 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier, 2015. Vol. 136, no 2, 216-220 p.
National Category
Hematology Cardiac and Cardiovascular Systems
URN: urn:nbn:se:umu:diva-103943DOI: 10.1016/j.thromres.2015.04.016ISI: 000363953000008PubMedID: 25935649OAI: diva2:816792
Available from: 2015-06-04 Created: 2015-06-04 Last updated: 2016-09-28Bibliographically approved
In thesis
1. Warfarin treatment quality in stroke prevention
Open this publication in new window or tab >>Warfarin treatment quality in stroke prevention
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]


Ischemic stroke is a serious condition often associated to presence of atrial fibrillation (AF). Use of anticoagulants for AF patients greatly reduces the risk of stroke. Warfarin is the most commonly used anticoagulant in Sweden. The aim of this thesis was to study the impact of warfarin treatment quality in Swedish stroke prevention.


Study I, II and IV were relatively large multicentre, retrospective, cohort studies based on Swedish registries, especially AuriculA, a quality register for AF and anticoagulation. Background data as well as bleeding and thromboembolic complications were retrieved from the National Patient Register. The Cause of Death Register was used in study II and IV. The Swedish Prescribed Drug Register was used in study IV, for data on concomitant acetylsalicylic acid (ASA) use. Study period was January 1, 2006, to December 31, 2011. Study III enrolled all warfarin treated AF patients in Sundsvall, registered in AuriculA on January 1, 2010. This smaller cohort was followed until discontinuation or study-stop December 31, 2013. All used data were collected from each patient’s medical record.


The annual risk of major bleedings and thromboembolic events for warfarin treated patients, including all different indications for warfarin, was relatively low (2.24% and 2.66%), with incidence of intracranial bleeding of 0.37% per treatment year. The overall mean time in therapeutic range (TTR) was 76.5%. Patients started on warfarin due to AF had a mean TTR of 68.6%, with an annual risk of major bleeding and thromboembolic events of 2.23% and 2.95%, and with 0.44% annual risk of intracranial bleeding. No significant differences in overall complications were found when comparing treatment monitored in anticoagulation clinics (ACC) with treatment monitored in primary health care centers (PHCC). There were significantly increased risk of both overall major bleedings and thromboembolic events for those warfarin treated AF patients receiving additional ASA treatment, having individual TTR (iTTR) below 70%, or having high international normalized ratio (INR) variability. AF patients with low INR variability had generally lower complication rates, compared with patients with high INR variability. There were however no alteration on cumulative incidence of complications due to INR variability, for AF patients with iTTR ≥70%. The overall proportion of persistence to warfarin treatment for stroke patients with AF was found to be 0.69 after 2 years treatment and 0.47 after 5 years. Stroke patients with diagnosed dementia at baseline were more than two-times likely of discontinuing warfarin than others. Excessive alcohol use, chronic obstructive pulmonary disease, cancer and chronic heart failure were baseline diagnoses each associated with over 20% increased risk of treatment discontinuation. Lower persistence to treatment was linked to increasing start-age and CHA2DS2-VASc scores. As documented reasons for warfarin treatment discontinuation in AF patients, we found regained sinus rhythm as the most common addressed cause (31.2%), followed by problematic monitoring and bleedings. We estimated that only half (49.5%) of the treatment discontinuations were clinically well motivated.


Quality of Swedish warfarin treatment in initiated stroke prevention is high, with generally low rates of complications and high TTRs, no matter treatment in ACC or PHCC, including high long time persistence to warfarin in secondary stroke prevention. For better outcome in future warfarin stroke prophylactic treatment clinicians should aim for iTTRs above 70%, avoid additional ASA therapy, support fragile patients like those with excessive alcohol use and dementia, and base decisions on treatment discontinuations on solid medical arguments.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2016. 50 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1827
Anticoagulation, atrial fibrillation, complications, international normalized ratio (INR) variability, persistence, stroke, time in therapeutic range (TTR), treatment quality, warfarin
National Category
Cardiac and Cardiovascular Systems Hematology
Research subject
Medicine, cardiovascular disease
urn:nbn:se:umu:diva-125998 (URN)978-91-7601-513-1 (ISBN)
Public defence
2016-10-21, Aulan, Utbildningslokalerna 1 trp, Sundsvalls sjukhus, Sundsvall, 13:00 (Swedish)
Available from: 2016-09-30 Created: 2016-09-26 Last updated: 2016-09-29Bibliographically approved

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Björck, FredrikSandén, PerSjälander, Anders
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