Warfarin for stroke prevention in elderly patients with atrial fibrillation

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By Douglas J Lanska MD MS MSPH

Article 1 under review: Hylek EM, D'Antonio J, Evans-Molina C, Shea C, Henault LE, Regan S. Translating the results of randomized trials into clinical practice: the challenge of warfarin candidacy among hospitalized elderly patients with atrial fibrillation. Stroke 2006;37:1075-80.

Purpose: To prospectively determine the use of antithrombotic therapy (and reasons for not using warfarin therapy where applicable) in a contemporary cohort of patients with atrial fibrillation at the time of hospital discharge.

Methods: Patients with atrial fibrillation were prospectively identified at a large, urban, university teaching hospital and followed until hospital discharge. Prescription of antithrombotic therapy was ascertained from the discharge summary and the electronic discharge medication list. The reason for not prescribing warfarin (if applicable) was recorded as stated in the discharge summary, or if absent or ambuiguous there, was clarified by inquiry of the treating physician.

Eligibility criteria:

  • At least 65 years of age
  • Atrial fibrillation verified by EKG
  • Not taking warfarin on admission
  • No other indication for long-term warfarin therapy
  • Longitudinal care provided by a physician at the study institution [to (1) minimize referral bias of more complex procedure-oriented patients; (2) ensure that the anticoagulation decision would no be deferred to the patient's outside physician; and (3) endure access to the ambulatory and hospital medical records.]

Results: 426 patients met eligibility criteria, but 21 died before discharge leaving 405 study patients. Most patients were admitted due to symptoms related to an uncontrolled ventricular rate.

Antithrombotic therapy at discharge:

Warfarin 51%
Antiplatelet therapy 38%
None 11%

Only about half of the study patients were started on warfarin (n=206; 51%), with the proportion varying significantly by age:

Age (years) Started on warfarin
65-69 75%
70-79 59%
80-89 45%
90 and older 24%

Patients started on warfarin were more often younger, male, with new onset atrial fibrillation, and without a history of hemorrhage or cognitive impairment. Almost a quarter of patients (22%) not started on warfarin had at least 1 fall that resulted in head trauma or fracture, compared to only 4% of those started on warfarin.

Independent predictors of not receiving warfarin

  • Older age
  • Cognitive impairment
  • History of falling
  • History of hemorrhage
  • Advanced malignancy

Physician-cited reasons for not prescribing warfarin

  • Hemorrhage (33%)
    - Recurrent (16%)
    - Current (8%)
    - Past intracranial (4%)
    - Past other (5%)
  • Falls* (32%)
  • Patient refused or history of nonadherence (14%)
  • Advanced illness, comfort care (8%)
  • Cognitive impairment (3%)
  • Alcohol abuse (2%)
  • Other (8%)
    - Intracranial mass
    - Labile hypertension
    - Previous hypersensitivity reaction
    - Anticipated procedures/surgery
    - Normal sinus rhythm after cardioversion (2%)
    - Pericarditis

*More than half (53%) of patients with falls as the physician-cited reason had at leat 1 spontaneous fall that resulted in closed head trauma or a fracture.