Commentary: Caution needed in introducing warfarin treatment

Effects of patients' preferences on the treatment of atrial fibrillation: observational study of patient-based decision analysis

OBJECTIVE

To investigate the effect of patients' preferences in the treatment of atrial fibrillation by using individualized decision analysis in which probability and utility assessments are combined into a decision tree.

DESIGN

Observational study based on interviews with patients.

SETTING

8 general practices in Avon, England.

PARTICIPANTS

260 randomly selected patients aged 70 to 85 years with atrial fibrillation.

MAIN OUTCOME MEASURES

Patients' treatment preferences regarding anticoagulation treatment (warfarin sodium) after individualized decision analysis; comparison of these preferences with treatment guidelines on the basis of comorbidity and absolute risk and compared with current prescription.

RESULTS

Of 195 eligible patients, 97 participated in decision making using decision analysis. Among these 97, the decision analysis indicated that 59 (61%; 95% confidence interval, 50%-71%) would prefer anticoagulation treatment, considerably fewer than those who would be recommended treatment according to guidelines. There was marked disagreement between the decision analysis and guideline recommendations (kappa> or =0.25). Of 38 patients whose decision analysis indicated a preference for anticoagulation, 17 (45%) were being prescribed warfarin; on the other hand, 28 (47%) of 59 patients were not being prescribed warfarin, although the results of their decision analysis suggested they wanted to be.

CONCLUSIONS

In the context of shared decision making, individualized decision analysis is valuable in a sizable proportion of elderly patients with atrial fibrillation. Taking account of patients' preferences would lead to fewer prescriptions for warfarin than under published recommendations. Decision analysis as a shared decision-making tool should be evaluated in a randomized controlled trial.

The impact of patients' preferences on the treatment of atrial fibrillation: observational study of patient based decision analysis

OBJECTIVE

To investigate the impact of patients' preferences for the treatment of atrial fibrillation, by using individualised decision analysis combining probability and utility assessments into a decision tree.

DESIGN

Observational study based on interviews with patients.

SETTING

Eight general practices in Avon.

PARTICIPANTS

260 randomly selected patients aged 70-85 years with atrial fibrillation.

MAIN OUTCOME MEASURES

Patients' treatment preferences regarding anticoagulation treatment (warfarin) after individualised decision analysis; comparison of these preferences with treatment guidelines on the basis of comorbidity and absolute risk and compared with current prescription.

RESULTS

Of 195 eligible patients, 97 participated in decision making using decision analysis. Among these 97, the decision analysis indicated that 59 (61%; 95% confidence interval 50% to 71%) would prefer anticoagulation treatment-considerably fewer than those who would be recommended treatment according to guidelines. There was marked disagreement between the decision analysis and guideline recommendations (kappa=0.25 or less). Of 38 patients whose decision analysis indicated a preference for anticoagulation, 17 (45%) were being prescribed warfarin; on the other hand, 28 (47%) of 59 patients were not being prescribed warfarin although the results of their decision analysis suggested they wanted to be.

CONCLUSIONS

In the context of shared decision making, individualised decision analysis is valuable in a sizeable proportion of elderly patients with atrial fibrillation. Taking account of patients' preferences would lead to fewer prescriptions for warfarin than under published guideline recommendations. Decision analysis as a shared decision making tool should be evaluated in a randomised controlled trial.

Warfarin use among patients with atrial fibrillation

BACKGROUND AND PURPOSE

Warfarin reduces the rate of stroke among patients with atrial fibrillation. We sought to determine warfarin use within a population sample of elderly patients with atrial fibrillation.

METHODS

The Connecticut Peer Review Organization conducted a chart review of Medicare patients aged > or = 65 years with a history of atrial fibrillation before a hospitalization during the first 6 months of 1994.

RESULTS

Among 488 patients (308 women; 457 white; 173 aged > or = 85 years), 38% (184/488) had a relative contraindication to anticoagulation (history of bleeding, dementia, alcohol use, falls, cancer, or the need for nonsteroidal anti-inflammatory drugs). Among the remaining patients (with known atrial fibrillation, but without a contraindication), only 38% (117/304) had been prescribed warfarin. Of those not prescribed warfarin, 63% (117/187) were also not taking aspirin. There were 272 patients with at least one additional vascular risk factor and no contraindication to anticoagulation. Among these patients at moderate to high risk for stroke, anticoagulation had been prescribed in 40% (109/272). Overal, among those not prescribed warfarin, 58% (95/163) were not taking aspirin. Patients admitted with a stroke were more likely to be significantly underanticoagulated (with international normalized ratio < 1.5) (43.5% versus 20.9% for those without stroke; P < .005). Anticoagulation was most effective for those with an international normalized ratio > or = 2.0.

CONCLUSIONS

Warfarin anticoagulation with atrial fibrillation, even among "ideal" candidates, appears dramatically underutilized. In addition, among those prescribed warfarin, patients are often undertreated. Increased warfarin use among patients with atrial fibrillation represents an excellent opportunity for stroke prevention in the elderly.

Primary care physician-reported secondary and tertiary stroke prevention practices. A comparison between the United States and the United Kingdom

BACKGROUND AND PURPOSE

Stroke is a major healthcare problem in both the United States (US) and the United Kingdom (UK). Little comparative data are available concerning how generalist physicians in the two countries approach the management of patients at high risk of stroke.

METHODS

Contemporaneous surveys of random samples of primary care physician-reported stroke prevention practices were performed in the US and UK from 1993 to 1994. The US National Survey of Physician Practices for the Secondary and Tertiary Prevention of Ischemic Stroke included 254 noninternist primary care physicians. The UK Survey of the Care of Patients With Stroke in General Practice obtained responses from 661 general practitioners. The two surveys used many of the same questions, allowing for direct comparisons of reported stroke prevention practices between American and British physicians.

RESULTS

More than 80% of American physicians reported a variety of services (24-hour electrocardiography, echocardiography, brain CT scan, brain MR scan, carotid ultrasonography, cerebral angiography) as readily available. These same services were readily available to less than 10% of physicians in the UK (P < .001 for each comparison). Although physicians in the UK reported prescribing lower doses of aspirin for stroke prevention than physicians in the US, the proportions of physicians using aspirin were not different. In contrast, almost 70% of physicians in the US responded that they always or often anticoagulate patients with nonvalvular atrial fibrillation compared with 7% of British physicians (P < .001). Whereas 70% of American versus 14% of British physicians reported obtaining carotid ultrasound studies in patients with asymptomatic bruits (P < .001), physicians in the UK more commonly reported referring this type of patient to neurologists (46% versus 21%, P < .001). For patients with recent carotid-distribution transient ischemic attack or minor stroke, physicians in the US more commonly reported referral to neurologists (55% versus 45%, P = .022), referral to surgeons (39% versus 19%, P < .001), the performance of carotid ultrasonography (80% versus 11%, P < .001), echocardiography (45% versus 5%, P < .001), 24-hour electrocardiography (49% versus 4%, P < .001), brain CT scan (72% versus 3%, P < .001), and the prescription of anticoagulants (53% versus 4%, P < .001).

CONCLUSIONS

These data show significant differences in stroke prevention practices as reported by primary care physicians practicing in the US and UK. Some of these differences may be related to the relative availability of specific services in the two countries, potentially leading to overutilization in the US and underutilization in the UK in certain circumstances.

Anticoagulant treatment in primary health care in Finland

OBJECTIVE

To establish the prevalence of anticoagulant (AC) treatment, the indications, and the quality of care in primary health care.

DESIGN

A cross-sectional study, in which patients on AC treatment were identified from laboratory records. The main and second indications for AC treatment and the last value of the AC-test were taken from medical records.

SETTING

Eight Finnish health centres with a total population of 182091 inhabitants.

RESULTS

A total of 1255 patients on AC treatment were identified, 48% of them men. The mean age was 68.9 years. The age-adjusted prevalence of AC treatment was 0.65%. The commonest main indication was atrial fibrillation (38%). It was the main or second indication in 591 patients (age-adjusted prevalence 0.30%). The next commonest main indication was deep vein thrombosis (15%), followed by pulmonary embolism (8%). A total of 274 (22%) patients were anticoagulated for cerebral circulatory disturbances. 86% of the latest prothrombin time values fell within recommended ranges.

CONCLUSION

The prevalence of AC treatment in Finland seems to be high. The proportion of patients with atrial fibrillation is high, differing from the results in other countries. The monitoring of AC-treatment as the general practitioner's responsibility functions well. The quality of care is good, even in older age groups.

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