Warfarin persistence among atrial fibrillation patients - why is treatment ended?

Prevalence of atrial fibrillation and reasons for undertreatment with oral anticoagulants

OBJECTIVES

To investigate the prevalence of atrial fibrillation (AF), the proportion of AF patients not receiving oral anticoagulation (OAC) and reasons for abstaining from OAC treatment.

METHODS

A retrospective cross-sectional study of patients aged 18 years or older with an AF diagnosis on June 1st 2020 in Västernorrland County, Sweden. AF diagnosis was retrieved using the ICD10 code I.48, and medical records were reviewed for comorbidities and documented reasons to abstain OAC treatment.

RESULTS

Of 197 274 residents in Västernorrland County, 4.7% (9 304/197 274) had a documented AF diagnosis. Of these, 19% (1 768/9 304) had no OAC treatment, including 4.2% (393/9 304) with no indication, 2.5% (233/9 304) with a questionable and 2.5% (231/9 304) with a documented clear contraindication for OAC. In total 9.8% (911/9 304) were not treated with OAC despite indication and no reasonable documented contraindication, thus 90.8% (8 447/9 304) of all AF-patients were eligible for OAC treatment. Common reasons for abstaining treatment without reasonable contraindication were present sinus rhythm in 13.7% (125/911), perceived not an OAC candidate in 10.6% (97/911) and anemia in the past in 4.3% (39/911).

CONCLUSIONS

In the population of Västernorrland County, a very high AF prevalence of 4.7% was found, of which just over 90% would theoretically benefit from OAC treatment. This is higher than previously reported and stresses the importance of stroke prevention in this large patient group.

Missed Opportunities to Initiate Oral Anticoagulant in Atrial Fibrillation: Insights from Australian Acute Coronary Syndrome Registries

BACKGROUND

Many patients with atrial fibrillation (AF) do not receive oral anticoagulant (OAC) therapy. The aims of this study were to 1) document receipt of OAC among patients with a history of AF admitted with an acute coronary syndrome (ACS); and to 2) determine whether hospital admission was associated with an improvement in prescription of OAC therapy.

METHODS

Using Australian data from the Cooperative National Registry of Acute Coronary Care, Guideline Adherence and Clinical Events (CONCORDANCE) and Global Registry of Acute Coronary Events (GRACE) registries, 1,479 patients with a history of AF presenting with an ACS were separated into two groups: aspirin monotherapy/no therapy (No OAC) or oral anticoagulant ± aspirin (OAC). Clinical characteristics and in-hospital treatments and outcomes were compared.

RESULTS

Of 1,479 patients, 532 (36%) with a history of AF presented on OAC with the remainder receiving antiplatelet (n=580 [39%]) or no antithrombotic therapy (n=367 [25%]). Treatment with OAC prior to presentation increased during the 18 years of the study (27% to 56%, p=0.0002). Ninety-five per cent (95%) of the OAC group had a CHA2DS2-VA score >1 vs 88% of the No OAC group (p<0.001). Patients receiving OAC had a lower prevalence of bleeding risk factors than no OAC patients (p<0.001). Only 39% of this cohort was discharged on an OAC, although this increased during the observational period (26-61%, p≤0.0001).

CONCLUSION

In patients presenting with an ACS with a history of AF, receipt of OAC has improved over time but remains suboptimal. There is minimal escalation in provision of OAC therapy during hospital care, indicating missed opportunities to address this evidence practice gap.

Impact of prescription patterns of antithrombotic treatment on atrial fibrillation-related ischemic stroke

OBJECTIVE

To analyze the temporal trends of atrial fibrillation (AF)-related ischemic stroke (IS) and their relationship with the prescription patterns of antithrombotic treatment from 2013 to 2019 in the Health Assistance Area of a regional hospital.

METHODS

First, a retrospective ecological study of aggregate data to analyze the annual incidence of IS between 2013 and 2019 was performed. Second, we selected those patients diagnosed with AF between 2013 and 2019 and performed a retrospective longitudinal study to assess the role of antithrombotic therapy in the development of AF-related IS.

RESULTS

During this period, whereas the annual incidence of IS remained stable (from 1.3 in 2013 to 1.2 cases per 1000 inhabitants in 2019; adjusted P for trend .829), the annual incidence of AF-related IS decreased over time (from 23.8 to 18.8 cases per 1000 inhabitants, respectively; adjusted P for trend .001). Among AF patients, the use of direct oral anticoagulants increased from 5.5% to 46.8%, while the prescription of antiplatelets and vitamin K antagonists decreased from 21.9% to 6.0% and from 63.8% to 36.1%, respectively. Overall, the use of oral anticoagulants increased from 69.3% to 82.9%; p < .001. Patients under antiplatelet agents had a higher probability of presenting IS than those patients taking oral anticoagulants, either vitamin K antagonists or direct oral anticoagulants (adjusted OR 1.89; 95% CI 1.52-2.37; p < .001).

CONCLUSIONS

The prescription of oral anticoagulants, particularly direct oral anticoagulants, has increased from 2013 to 2019 in our Health Assistance Area. This increase might partially explain the reduction in AF-related IS.

Reducing Stroke Risk in Atrial Fibrillation: Adherence to Guidelines Has Improved, but Patient Persistence with Anticoagulant Therapy Remains Suboptimal

Atrial fibrillation (AF) is a significant risk factor for avoidable stroke. Among high-risk patients with AF, stroke risk can be mitigated using oral anticoagulants (OACs), however reduction is largely contingent on physician prescription and patient persistence with OAC therapy. Over the past decade significant advances have occurred, with revisions to clinical practice guidelines relating to management of stroke risk in AF in several countries, and the introduction of non-vitamin K antagonist OACs (NOACs). This paper summarises the evolving body of research examining guideline-based clinician prescription over the past decade, and patient-level factors associated with OAC persistence. The review shows clinicians' management over the past decade has increasingly reflected guideline recommendations, with an increasing proportion of high-risk patients receiving OACs, driven by an upswing in NOACs. However, a treatment gap remains, as 25–35% of high-risk patients still do not receive OAC treatment, with great variation between countries. Reduction in stroke risk directly relates to level of OAC prescription and therapy persistence. Persistence and adherence to OAC thromboprophylaxis remains an ongoing issue, with 2-year persistence as low as 50%, again with wide variation between countries and practice settings. Multiple patient-level factors contribute to poor persistence, in addition to concerns about bleeding. Considered review of individual patient's factors and circumstances will assist clinicians to implement appropriate strategies to address poor persistence. This review highlights the interplay of both clinician's awareness of guideline recommendations and understanding of individual patient-level factors which impact adherence and persistence, which are required to reduce the incidence of preventable stroke attributable to AF.

Association of Warfarin Use With Lower Overall Cancer Incidence Among Patients Older Than 50 Years

IMPORTANCE

In cancer models, warfarin inhibits AXL receptor tyrosine kinase-dependent tumorigenesis and enhances antitumor immune responses at doses not reaching anticoagulation levels. This study investigates the association between warfarin use and cancer incidence in a large, unselected population-based cohort.

OBJECTIVE

To examine the association between warfarin use and cancer incidence.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study with subgroup analysis used the Norwegian National Registry coupled with the Norwegian Prescription Database and the Cancer Registry of Norway. The cohort comprised all persons (N = 1 256 725) born between January 1, 1924, and December 31, 1954, who were residing in Norway from January 1, 2006, through December 31, 2012. The cohort was divided into 2 groups-warfarin users and nonusers; persons taking warfarin for atrial fibrillation or atrial flutter were the subgroup. Data were collected from January 1, 2004, to December 31, 2012. Data analysis was conducted from October 15, 2016, to January 31, 2017.

EXPOSURES

Warfarin use was defined as taking at least 6 months of a prescription and at least 2 years from first prescription to any cancer diagnosis. If warfarin treatment started after January 1, 2006, each person contributed person-time in the nonuser group until the warfarin user criteria were fulfilled.

MAIN OUTCOMES AND MEASURES

Cancer diagnosis of any type during the 7-year observation period (January 1, 2006, through December 31, 2012).

RESULTS

Of the 1 256 725 persons in the cohort, 607 350 (48.3%) were male, 649 375 (51.7%) were female, 132 687 (10.6%) had cancer, 92 942 (7.4%) were classified as warfarin users, and 1 163 783 (92.6%) were classified as nonusers. Warfarin users were older, with a mean (SD) age of 70.2 (8.2) years, and were predominantly men (57 370 [61.7%]) as compared with nonusers, who had a mean (SD) age of 63.9 (8.6) years and were mostly women (613 803 [52.7%]). Among warfarin users and compared with nonusers, there was a significantly lower age- and sex-adjusted incidence rate ratio (IRR) in all cancer sites (IRR, 0.84; 95% CI, 0.82-0.86) and in prevalent organ-specific sites (lung, 0.80 [95% CI, 0.75-0.86]; prostate, 0.69 [95% CI, 0.65-0.72]; and breast, 0.90 [95% CI, 0.82-1.00]). There was no observed significant effect in colon cancer (IRR, 0.99; 95% CI, 0.93-1.06). In a subgroup analysis of patients with atrial fibrillation or atrial flutter, the IRR was lower in all cancer sites (IRR, 0.62; 95% CI, 0.59-0.65) and in prevalent sites (lung, 0.39 [95% CI, 0.33-0.46]; prostate, 0.60 [95% CI, 0.55-0.66]; breast, 0.72 [95% CI, 0.59-0.87]; and colon, 0.71 [95% CI, 0.63-0.81]).

CONCLUSIONS AND RELEVANCE

Warfarin use may have broad anticancer potential in a large, population-based cohort of persons older than 50 years. This finding could have important implications for the selection of medications for patients needing anticoagulation.