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Impact of adverse events on prescribing warfarin in patients with atrial fibrillation: matched pair analysis

BMJ 2006; 332 doi: https://doi.org/10.1136/bmj.38698.709572.55 (Published 19 January 2006) Cite this as: BMJ 2006;332:141

Rapid Response:

Barriers to the use of warfarin in non-valvular atrial fibrillation

Anticoagulation is under-utilised in the treatment of non-valvular
atrial fibrillation (NVAF). The study by Choudhry et al (1) suggests that
adverse outcomes from anticoagulation have greater influence on the
management of NVAF than occurrences of avoidable ischaemic stroke. The
authors speculate that this result arises from undue fear or concern about
adverse consequences of anticoagulation.

We are conducting a representative national survey of 1000 Australian
general practitioners (GPs) addressing how fear of anticoagulation affects
management of NVAF. Our preliminary findings indicate that aversion to
the risk of intracranial haemorrhage was substantial. Doctors are overly
cautious in prescribing anticoagulation where there is a perceived risk of
major and even minor bleeding even when the benefits of anticoagulation
outweigh the risks.

In 207 early responses, 45.9% of GPs reported the experience of an
ischaemic stroke in their NVAF patients without anticoagulation. Only 13%
reported experiencing an intracranial haemorrhage in NVAF patients on
anticoagulants. Over half of GPs (54.1%) expected to feel equal
responsibility for either an intracranial haemorrhage in a patient on
anticoagulants or a fatal or disabling ischaemic stroke without
anticoagulation. Nineteen percent would feel more responsible for an
intracranial haemorrhage.

When asked to select treatment for a hypothetical NVAF patient at
‘high’ risk of stroke (2), 72.5% of GPs would appropriately select
warfarin. A perceived risk of bleeding markedly reduced selection of
warfarin even when the risk of bleeding was acceptable according to best
available evidence (3,4). In the presence of a minor falls risk that
would not contraindicate anticoagulation (3) fewer than half of GPs
(46.6%) selected warfarin. Only 28% would anti-coagulate the patient at
high risk of stroke with a history of recurrent nose-bleeds. Only 20.3%
of GPs would anti-coagulate such a patient with a previously treated
peptic ulcer bleed.

Implementing evidence-based management of NVAF is proving difficult
and the potential to reduce stroke risk is yet to be fully realised (5).
Our preliminary findings support Choudhry et al’s (1) assertion that there
is a profound psychological dimension in the under-prescribing of
anticoagulants for NVAF. Any strategy to improve the evidence-based
management of NVAF will need to address the excessive concerns clinicians
have about anticoagulation. We need to reduce anxiety about ‘acts of
commission’ in the management of NVAF.

1. Choudhry NK, Anderson GM, Laupacis A et al. Impact of adverse
events on prescribing warfarin in patients with atrial fibrillation:
matched pair analysis. BMJ 2006; 332; 141-145.

2. Gage BF, Waterman AD, Shannon W, et al Validation of clinical
classification schemes for predicting stroke: results from the National
Registry of Atrial Fibrillation. JAMA 2001; 285:2864-70.

3. Gage BF. Birman-Deych E. Kerzner R. Radford MJ. Nilasena DS. Rich
MW. Incidence of intracranial hemorrhage in patients with atrial
fibrillation who are prone to fall. American Journal of Medicine. 2005;
118:612-7

4. Man-Son-Hing M et al Choosing anti-thrombotic therapy for elderly
patients with atrial fibrillation who are at risk of falls. Archives of
Internal Medicine 1999; 159: 677-85.

5. Evans A, Davis S, Kilpatrick C et al. The morbidity related to
atrial fibrillation at a tertiary centre in one year: 9.0% of all strokes
are potentially preventable. Journal of Clinical Neuroscience 2002; 9:
268-272

Competing interests:
None declared

Competing interests: No competing interests

26 January 2006
Melina Gattellari
Research Fellow
John M. Worthington, Nicholas A. Zwar, Sandy Middleton
School of Public Health & Community Medicine The University of New South Wales, KENSINGTON NSW 2052