Age and Ageing Advance Access originally published online on July 26, 2007
Age and Ageing 2007 36(5):598-599; doi:10.1093/ageing/afm082
Comment on the WASPO study
SIR—Comparing the effects of aspirin versus warfarin in a group of octogenariansshould yield clinically useful information to aid decision-making in an age group where it is often difficult, even after risk stratification, to judge if warfarin is really the appropriate choice for the individual patient sitting before you in the clinic or on the ward. It would, therefore, have been helpful if Rash and colleagues had reported the CHADS2 risk stratification scores for the two patient groups, as judging from the baseline characteristics data in Table 1 these study patients were predominantly at moderate stroke risk (CHADS2 score 1 and 2) with an annual stroke risk of 4% or less [1, 2]. While this level of risk seems in keeping with the reported results of this ‘relatively "fit" group of octogenarians’, it contrasts with the National Institute for Clinical Excellence (NICE)/Birmingham stroke risk stratification score, where the majority would have been classified as high-risk (8–12%) being aged over 75 years with co-morbidities of hypertension, diabetes or heart failure [3]. NICE stroke risk stratification and thromboprohylaxis guidelines suggest that these high-risk patients should be anticoagulated with warfarin.Applying CHADS2 risk stratification (rather than NICE scores) to these results is reassuring, as warfarin or aspirin 300 mg with routine proton pump inhibitor cover do seem to be acceptable alternatives for this group of patients. Asalluded to by Rash and colleagues, some of the NICE guidance remains puzzling with aspirin doses of 75 mg–300 mg suggested; use of the lowest 75 mg dose is not supported by the original AF and stroke prevention trials published in the late 1980s and early 1990s. Similarly, the NICE guidance has rather a ‘blunt’ riskstratification system where co-morbidities such as diabetes and vascular disease do not make an independent contribution, unlike in CHADS2. Given the limitations of this scoring, it may be better practice in octogenarians when making decisionson primary stroke prevention to use CHADS2 preferentially for this group of older patients.
The study group did appear rather atypical given the low percentage of diabetic patients (3% in the warfarin group and 5% in the aspirin group), compared with other studies that have found this co-morbidity in 16.5% of elderly patients [4]. Although diabetes is part of the CHADS2 risk stratification in AF, diabetic patients often have small vessel disease and consequently a higher risk of bleeding with warfarin thus influencing the choice between aspirin and warfarin for stroke prevention [5].
This is an interesting study but, as hinted at by the authors in their conclusion, has limited application in clinical practice. It does, however, highlight that with careful stratification of individual risks in AF and subsequent anticoagulation there is a group of patients traditionally viewed as ‘high-risk’ for such intervention who could safely decide to choose warfarin rather than aspirin.
1 Department of Elderly Medicine, St James's University Hospital, Leeds LS9 7TF, UK
2 School of Medicine, University of Leeds, Leeds LS2 9JT, UK
*To whom correspondence should be addressed Email: nigel.dudley{at}leedsth.nhs.uk
References
- Rash A, Downes T, Portner R, et al. A randomised controlled trial of warfarin versus aspirin for stroke prevention in octogenarians with atrial fibrillation (WASPO). Age Ageing (2007) 36:151–6.
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[Abstract/Free Full Text] - Lip GYH, Lane D, Van Walraven C, et al. Additive role of plasma von Willebrand factor levels to clinical factors for risk stratification of patients with atrial fibrillation. Stroke (2006) 37:2294–300.
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[Abstract/Free Full Text]
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