Initiation and persistence of warfarin or aspirin in patients with chronic atrial fibrillation in general practice: do the appropriate patients receive stroke prophylaxis?

Abstract

To cite this article: Gallagher AM, Rietbrock S, Plumb J, van Staa TP. Initiation and persistence of warfarin or aspirin in patients with chronic atrial fibrillation in general practice: do the appropriate patients receive stroke prophylaxis? J Thromb Haemost 2008; 6: 1500-6. Summary. Background: Practice guidelines recommend longterm stroke prophylaxis in patients with chronic atrial fibrillation (cAF). Objectives: To examine treatment initiation and persistence and factors that influence the choice of cAF treatment. Patients/methods: This study used the General Practice Research Database, including computerized medical records of general practitioners in the UK. Patients aged 40+ years with cAF after 1 January 2000 were included. Cox proportional hazards regression models evaluated initiation and treatment continuation over time of warfarin and aspirin. Treatment discontinuation was defined as no repeat prescription within a three-month period after the expected end of the treatment course. Results: The study population included 41 910 cAF patients. Elderly patients (aged 85+) were less likely to start warfarin [relative rate (RR) = 0.16, 95% confidence interval (CI) 0.15-0.18] and more likely to start aspirin (RR = 1.66, 95% CI 1.47-1.88) than patients aged 40-64 years. A history of dementia (RR = 0.28, 95% CI 0.17-0.44) and falls (RR = 0.76, 95% CI 0.70-0.83) also reduced the likelihood of warfarin initiation. Adjusting for age and gender, higher stroke risk (CHADS 2 score) was not found to be associated with initiation of warfarin or aspirin contrary to current guidelines recommendations. One-year persistence was 70% for warfarin and 50% for aspirin. Treatment persistence was higher in elderly patients using warfarin and aspirin. A higher CHADS 2 score was associated with improved persistence only with warfarin. Conclusions: The low likelihood of patients with cAF in general practice remaining on treatment long-term indicates that not all benefits as observed in clinical trials may be achieved in usual clinical practice.

Untreated atrial fibrillation in the United Kingdom: Understanding the barriers and treatment options

“…Overall, this study suggested that less than half (49.3%) of patients with a history of AF received an anticoagulant and that anticoagulant uptake increases through CHADS 2 score 0-3 and thereafter reaches a plateau [16]. These results are similar to those of another recent study [12] and represent an improvement compared to what had previously been described [32]. Nevertheless, if the treatment threshold for anticoagulation is a CHADS 2 score P1, this would include 84% of the AF population, which is significantly higher than the percentage of patients currently given anticoagulation.…”

Optimising stroke prevention in patients with atrial fibrillation: application of the GRASP-AF audit tool in a UK general practice cohort

“…6,7,18 Cowan et al report that 36.2% received antiplatelets alone; 5 suggesting that the prescription of antiplatelet therapy for stroke prevention in AF may vary markedly in the UK. The discrepancy in the proportions of patients receiving antiplatelet therapy between the present study and Cowan et al …”

“…These findings are similar to the results from two recent analyses of UK general practice 5,10 and a global survey of OAC, 6 but contrast with previous analyses of antithrombotic therapy by stroke risk. 17,18 This could suggest that the greater emphasis on risk stratifying patients advocated by guidelines is beginning to affect contemporary clinical practice, and that using the GRASP-AF tool, incorporating the CHA 2 DS 2 -VASc score, could help to identify those at risk of stroke and increase the use of appropriate OAC therapy.…”

“…6 Analyses of UK general practice suggest that there appears to have been a slight improvement in the number of high-risk patients with AF receiving OAC over the past few years. For example, an analysis of antithrombotic therapy initiation after 1 January 2000 from the UK General Practice Research Database (GPRD) by Gallagher et al 18 demonstrated that approximately 60% of patients with a high risk of stroke (CHADS 2 score ≥2) were not receiving OAC. A more recent analysis by Holt et al 10 reported that 53% of high-risk patients with AF received OAC, although this study did not use the GRASP-AF tool or report observed stroke risk, while the most recent analysis by Cowan et al using the GRASP-AF tool, suggests that only 34.0% of patients at high risk of stroke without contraindications to OAC are not prescribed it.…”

Risk of stroke and oral anticoagulant use in atrial fibrillation: a cross-sectional survey

“…[14][15][16] The authors were interested not only in the patterns of risk and levels of anticoagulant use, but also in the ability of primary care data to support risk estimation. A software tool (GRASP-AFGuidance on Risk Assessment and Stroke Prevention in Atrial Fibrillation) has been developed for UK general practices, 17 which produces lists of high-risk but untreated individuals.…”