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Anticoagulants may increase risk of stroke for CKD patients, study warns

GPs should weigh up risks and benefits before initiating anticoagulants as these may increase risk of ischaemic stroke and haemorrhage in chronic kidney disease patients, researchers have said.

The study, carried out by researchers in London, Surrey and New York, looked at just over 2,400 patients over the age of 65 with chronic kidney disease and a new diagnosis of AF who were taking anticoagulants.

The CKD patients were matched with AF patients who were not taking anticoagulants, and followed up for an average of just over 500 days. Just over 70% of the patients were on vitamin K antagonists and the remainder were on DOACs or low molecular weight heparin.

The researchers found that CKD patients on anticoagulants were almost three times more likely to suffer a stroke as those who were not, and over twice as likely to experience a haemorrhage. The incidence of stroke in patients on anticoagulants was 4.6 per 100 person years, compared to 1.5 in those who were not - which the researchers said was statistically significant.

They noted, however, that all-cause mortality was reduced in CKD patients on anticoagulants, suggesting that this ‘paradoxical’ finding may be due to anticoagulants leading to a lower rate of fatal strokes or a reduced number of myocardial events.

They said in the paper: ‘For the general population, overwhelming evidence from large scale randomised controlled trials supports oral anticoagulation in the context of atrial fibrillation for stroke thromboprophylaxis, and this has been universally adopted in clinical practice guidelines.

'However, this may not apply in patients with atrial fibrillation and concurrent chronic kidney disease.'

The researchers added: 'Given the present lack of guidelines, the decision to start anticoagulant treatment in patients with new onset atrial fibrillation should be made on an individual basis, weighing up the known risks and potential benefits and, where possible, taking into account patients’ wishes.’

Dr Shankar Kumar, lead author and academic clinical fellow and ST1 in radiology at University College London Hospitals NHS Foundation Trust, told Pulse that the most pressing need at the moment is more studies in the field in order to inform GP decision making going forward.

Until then, he said that 'weighing up the known risk factors and taking into account the benefits and risks on an individualised basis' was the most important thing for GPs to do.

Dr Terry McCormack, GP and cardiovascular lead in North Yorkshire, commented: 'The authors are calling for more research, and an individual approach to decision making in the meantime. I support the need for a careful approach in elderly people with renal dysfunction and I have enormous respect for [study co-author] Professor John Camm, a world leader in this field, but just hope this does not set back the use of anticoagulants to prevent stroke.'

The results come as GPs have in the past been urged to prescribe more preventative drugs for stroke patients, including anticoagulants, antihypertensives or statins.

But GPs were warned last year to exercise caution when prescribing anticoagulants after a study found that patients with contraindications were just as likely to be prescribed the drugs as those without risk factors.

BMJ; available online 14th February

Readers' comments (5)

  • Over 70% of patients were treated with warfarin but time on therapeutic range was not one of the matched clinical variables between the study and control groups.

    Pretty major flaw of the study in my opinion which renders the results next to useless.

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  • It would be expected to have more strokes in the at risk group, but studies in patients with a wide variety of conditions need to be done to balance the unthinking protocol driven increase in anticoagulation.

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  • I will continue to follow the totally medico-legally defensible NICE guidance and will not be considering anything else until this changes.

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  • NOOOOOOOOOOOOOOOOOOO! My poor little brain has tied itself in a knot now.

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  • If you look at the graph in this paper, specifically for all cause mortality, you might get a shock! It’s in figure 1
    http://www.bmj.com/content/356/bmj.j510

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