Use of antithrombotics means more intracerebral haemorrhagic stroke deaths in over 75s

A study suggests that the number of pensioners over 75 dying from intracerebral haemorrhagic stroke has increased in the last 25 years due to use of antithrombotic drugs.

The findings are published early Online and in an upcoming edition of The Lancet Neurology

Antithrombotic drugs, such as aspirin, reduce the risk of strokes and heart attacks in people who are known to have vascular disease. However, there is no clear evidence of overall benefit in low risk healthy individuals, due mainly to the risk of bleeding complications, which are particularly common in the elderly. Yet, many healthy older people chose to take regular aspirin particularly in the hope of preventing a stroke.

Professor Peter Rothwell and colleagues at the University Department of Clinical Neurology, University of Oxford, UK, studied data from the Oxford Community Stroke Project (1981-85) and the Oxford Vascular Study (2002-06). They investigated incidence of intracerebral haemorrhagic stroke over time, for patients both above and below 75 years old, together with associated risk factors such as hypertension (high blood pressure) and medications.

The authors say: “Intracerebral haemorrhage is often disabling or fatal, and despite the promise of new acute therapies, prevention must remain the primary goal.”

The researchers found that incidence of such strokes associated with hypertension for both under and over 75s combined had fallen, largely due to a fall in average blood pressure over the time period of the study. But the proportion of cases in over-75s only had remained similar, in part due to increased intracerebral haemorrhage associated with antithrombotic (anti-blood clotting) drug use.

Whilst only 4% of patients with intracerebral haemorrhage were taking antithrombotic drugs in the 1981-85 study, this proportion had increased to 40% by the 2001-06 study. This increased use could explain the absence of the expected fall in rates of intracerebral haemorrhage in older patients that should have occurred due to falling average blood pressures over the 25 years.

The authors say their findings suggest that increasing use of antithrombotic agents may soon overtake poorly controlled blood pressure as the major risk factor for intracerebral haemorrhagic stroke in the over 75s.

The authors conclude: “This potential rise in the burden of intracerebral haemorrhage would not have been predicted from previous studies of mortality data, which were limited to the population under 75 years.

“Since at least two thirds of cases of intracerebral haemorrhage and 50% of all strokes occur above this age, it is essential to include the older population in studies of stroke.

“Antithrombotic drugs, such as aspirin, are undoubtedly of overall benefit in older patients with a definite indication, such as a previous heart attack or stroke, but our results emphasise the need for caution in advising widespread use of daily prophylactic aspirin in healthy older people who are not known to have vascular disease.”

In an accompanying comment, Dr Dawn Kleindorfer, director of the Stroke Prevention Programme Greater Cincinnati/Northern Kentucky, USA, says: “Stabilisation of the incidence of stroke, especially the high morbidity and mortality associated subtybe of intracerebral haemorrhagic stroke, is not good news. As our population continues to age, the actual number of events will continue to increase, and overwhelm our already overburdened healthcare systems.

“We need to find new and better ways to prevent stroke and change behaviour of patients and physicians so that this stable incidence trend does not continue.”

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