More work needed to reduce strokes due to atrial fibrillation in UK

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A study published in BMJ Open has found that although the number of strokes has fallen in the UK, more needs to be done to reduce the risk of stroke in patients with atrial fibrillation. Additionally, it seems that while the use of anticoagulants does not increase with increasing CHADS2 (congestive heart failure, hypertension, age, diabetes, stroke) score in patients with atrial fibrillation, the use of antiplatelets does increase

Sally Lee, MAPOR, Boehringer Ingelheim, Bracknell, UK, and her fellow authors reviewed the number of strokes between 1999 and 2008 in the UK, using the UK General Practice Research Database (which contains longitudinal patient primary care records and has information on demographics, diagnoses, referrals, prescribing and health outcomes for more than 3 million patients). They found that 32,151 patients had a first stroke in this timeframe and that the incidence of first stroke was reduced by 30% in the study period (from 1.48 per 1000 patient years in 1999 to 1.04 per 1000 patient years in 2008; p<0.001). The incidence of stroke was also reduced in patients aged 80 years or older, falling by 42% (from 18.97 per 1000 patient years to 10.97 per 1000 patient years during the nine-year period).

Death from first stroke was also reduced (from 21% in 1999 to 12% in 2008), a trend that was observed in both men and women. However, death from first stroke was higher in patients with atrial fibrillation: 27% of women and 19% of men with “coded” atrial fibrillation died within 56 days of their first stroke compared with 18.6% and 11.3%, respectively, in the overall cohort.

Another concerning finding in patients with atrial fibrillation was that only 25% with coded atrial fibrillation were prescribed anticoagulants prior to their stroke and that anticoagulant prescribing did not increase with increasing CHADS2 score. In fact, according to Lee et al, anticoagulants may be overused in the patients at low risk of stroke. They reported: “There was a relatively high, and possibly inappropriate, level of anticoagulant prescribing in lower risk patients (those with a CHADS2 score of 0).” They add that previous studies have also shown a high use of anticoagulants in patients at low risk of stroke in primary care in the UK.

While the use of anticoagulants did not appear to increase with increasing CHADS2 score, the use of antiplatelet agents did increase with increasing CHADS2 score. Lee et al suggested that these data may indicate that GPs in the UK respond to the risk of thromboembolism by using antiplatelets rather than anticoagulants. They added: “Use of anticoagulants was lower in women than men despite women’s higher CHADS2 scores. Women were older than men in the atrial fibrillation patient population and lower use of anticoagulants might reflect prescriber concerns that anticoagulants are more dangerous in the elderly. However, it has been shown that there is no significant difference in bleeding risk between warfarin and aspirin in patients aged over 75 years.”

Lee et al also reported that that use of interventions, particularly lipid-lowering agents and antihypertensive agents, to reduce the risk of stroke, has consistently increased between 1999 and 2008. They concluded: “Improved drug treatment in primary care is likely to be a major contributor to this [reduction in stroke incidence], with better control of risk factors both before and after incidence stroke. There is, however, scope for further improvement in risk factor reduction in high-risk patients with atrial fibrillation.”

Martin Cowie, professor of cardiology at Imperial College, London, UK and one of the investigators, told Cardiac Rhythm News: “More needs to be done to identify patients with atrial fibrillation and to place them on anticoagulation if appropriate. Failing to do so this leaves too many people with a high risk of disabling stroke and may be fatal.”

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