Study highlights risks of stopping anticoagulants in older patients

For patients with atrial fibrillation, the risk of stroke or heart attack from stopping anticoagulants usually outweighs the risk of bleeding, according to new findings from the University of Bath.

Clinicians often worry about the dangers of prescribing blood thinning medications to older patients, due to concerns about falls and major bleeding, however new research from the University of Bath – funded by the Dunhill Medical Trust – suggests that for patients with the common heart condition atrial fibrillation (AF), the health risks of not taking these drugs are significantly higher than the risk of a life-threatening bleed.

AF is associated with a fivefold increase in the risk of stroke, with estimates suggesting the condition contributes to 20,000 strokes a year in the UK. It also increases the risk of heart attacks and death. Blood thinners – otherwise known as anticoagulants – are highly effective in managing AF and preventing strokes and other complications.

Older people also tend to fall more frequently, with falls being a leading cause of injury among adults aged 65 and older. These can lead to serious injuries, such as hip fractures and head injuries.

However, the new study, published today in Heart, found that contrary to popular medical belief, stopping anticoagulants for patients aged 75 and over does not change the risk of major bleeds. These findings are important for clinicians to factor into their prescribing behaviour, according to the study's authors.

"Prescribers need to consider the increased risk to patients of coming off anticoagulants, including stroke," said Dr. Anneka Mitchell, who conducted the research from the University of Bath and is a visiting researcher at the University's Department of Life Sciences.

Rising cases

Cases of AF are rising in all age groups but particularly among people aged 85 years and over. In this age group, the number of people diagnosed with the condition doubled in men from 11.6% to 22.1% between 2000 and 2016, and increased in women from 9.6% to 16.5%. There is no data available to show trends from 2016.

Though there is a large body of evidence to support the use of blood thinners for older people with AF, the new study is believed to be the first to measure patient outcomes when anticoagulant medication is stopped.

Dr. Mitchell's study analyzed data from the UK Clinical Practice Research Datalink (a research dataset that includes anonymized patient data from some UK general practices) between 2013 and 2017, focusing on patients aged 75 and older who were newly prescribed anticoagulants.

It found that the risks of stroke and death were three times higher during periods when patients were not receiving anticoagulation therapy. The risk of heart attacks was nearly double compared with periods when patients were treated with anticoagulants.

Warfarin versus direct oral anticoagulants

Dr. Mitchell – who is affiliated with ReMind UK, the Bath-based charity and research institute and also works as a clinical pharmacist at University Hospitals Plymouth NHS Trust – believes that as well as concern about falls, many clinicians base their decisions to withhold anticoagulants on the historic experience of patients taking the anticoagulant warfarin.

This medication – the only available option for treating AF until 2012 – is associated with a complex medication regimen, along with dietary restrictions and frequent blood-tests, making treatment difficult for many older patients.

Since 2013, however, a new family of drugs called direct oral anticoagulants (DOACs) have become the first line option for most patients. DOACs are as effective and safe as warfarin – sometimes more so – and are far more straightforward to take.

For example, apixaban (a DOAC) has a lower risk of significant bleeding than warfarin, so for many older patients with AF, this would be an excellent medication.

Our findings highlight the critical need for clinicians to carefully consider the risks of stopping anticoagulation therapy in older patients. Despite concerns about bleeding, this study suggests that discontinuing anticoagulation does not significantly affect the risk of major bleeding but does increase the risk of serious events such as stroke and death."

Dr. Anneka Mitchell

She added: "Both the risks and benefits of medication must be discussed fully with patients before a medic stops prescribing anticoagulants, so that both doctor and patient are making a shared and informed decision. This study underscores the importance of evaluating the consequences of deprescribing anticoagulants, particularly in older adults who are at higher risk of adverse outcomes."

Impacting the lives of older patients

Dr Anita McGrogan who led the research team from the Department of Life Sciences at Bath, said: "Older patients were poorly represented in clinical trials that evaluated the efficacy and safety of DOACs before these products were licensed, and those who were included were healthier than many people in the target group for prescribing. Because of this, the safety of these medications for people aged 75-plus was not evaluated, and many chose to avoid prescribing them for older people.

"This study has produced important results that will have an impact on patients in the future. It has filled the information gap by looking at anonymous data on 20,167 people aged over 75 years, collected by GPs. It clearly demonstrates the value of using big data to investigate important clinical questions, especially in vulnerable populations."

Dr Tomas Welsh, an academic geriatrician at Royal United Hospitals Bath and research & medical director at ReMind, hopes the new research will provide both clinicians and patients with better evidence to inform their decisions regarding anticoagulants. He noted that, until now, clinicians advising patients to stop taking blood thinners were unable to quantify the increased risk of stroke.

"These data help patients and clinicians have a firmer grasp of the risks that they are being exposed to," he said.

Dr Welsh also stressed that new-generation blood thinners were not always the right course of action for frail, older people.

"Suspending any medication or reducing the use of multiple medications in a frailer older patient is always a nuanced and individual discussion," he said.