Part II of II: SHOULD EVERYONE TAKE ASA?

PART II OF II DETRIMENTAL EFFECTS OF ASPIRIN

SHOULD EVERYONE TAKE ASA?

Aspirin and other platelet aggregation inhibitors may increase the likelihood of asymptomatic cerebral microbleeds among older adults. Microbleeding has gained recognition over the past decade as a marker of small-vessel disease in the brain.

The analysis involved 1,062 participants in the longitudinal, population-based Rotterdam Scan Study, all age 60 or older and free of dementia. They underwent MRI over a period of roughly one year to assess the presence and location of microbleeds. Pharmacy records showed that 34.2% had used an antithrombotic drug as an outpatient in the years before their MRI. The study determined that these antithrombotic drug users were more likely to have cerebral microbleeds than nonusers after adjustment for age and sex (odds ratio 1.55, 95% confidence interval 1.14 to 2.09).The association remained after additional adjustment for cardiovascular risk (OR 1.56, 95% CI 1.15 to 2.12).

Antithrombotics were also linked to presence of brain infarcts and high white matter lesion volume, but exclusion of participants with a known history of cerebrovascular disease attenuated these associations.

Location appears to be important: strictly lobular microbleeding suggests cerebral amyloid angiopathy, in which accumulation of amyloid protein leads to degeneration of smooth muscle cells and increases risk of ruptures and hemorrhages. Aspirin users in the population-based study were also more likely to show microbleeding limited to lobular areas of the brain, the researchers reported.

Past microbleeding -- indicated by small deposits of the iron-storing protein hemosiderin on brain scans -- was 71% more common with use of platelet aggregation inhibitors than without antithrombotic drugs.

Exclusive use of platelet aggregation inhibitors accounted for most of the antithrombotics (23.1% of the cohort). Another 5.9% exclusively used anticoagulants. These were overwhelmingly warfarin (Coumadin) and other vitamin K antagonists rather than heparin.
Although not significant, anticoagulants displayed a magnitude of microbleeding risk (OR 1.49, 95% CI 0.81 to 2.67) similar to platelet aggregation inhibitors (OR 1.71, 95% CI 1.21 to 2.41) in the fully adjusted model.

One researcher speculated that "It may be that microbleed formation is more dependent on the sealing of small-vessel-wall defects by platelet aggregation than it is on clot stabilization."

Source reference:
Vernooij MW, et al "Use of antithrombotic drugs and the presence of cerebral microbleeds: The Rotterdam scan study" ARCH NEUROL 2009; 66: DOI: 10.1001/archneurol.2009.42.

COMMENT:
This brings up the question as to the indications for everyone—healthy with minimal cardio-vascular risks and those with greater risks taking small doses of aspirin as prophylaxis for heart attacks and stroke, as well as the advanced elderly.

Aspirin is enormously useful as a prophylactic for cardiovascular events including myocardial infarction and ischaemic stroke. There has been concern, however, that aspirin can also increase hemorrhagic strokes and cause gastrointestinal bleeding. This study investigated the balance of positive and negative effects, and the results indicate no overwhelming difference. For individual patients, therefore, it depends on whether it is better to risk an MI or a gastrointestinal bleed says findings in the Lancet, Volume 373, Issue 9678, Pages 1849 - 1860, 30 May 2009 doi:10.1016/S0140-6736(09)60503-1

These findings "challenge guidelines that endorse the use of aspirin for primary prevention as a general public health policy and reinforce the need to take each patient's preferences and goals.

Researchers undertook an analysis of six primary prevention trials encompassing some 95,000 individuals at low-average risk assigned to take aspirin or no aspirin. Aspirin was associated with a significant reduction in risk for serious vascular events (0.51% vs. 0.57% per year), but the net effect on stroke was not significant. Aspirin increased risks for major gastrointestinal and extracranial bleeding. Therefore everyone using aspirin in the primary prevention of cardiovascular disease is "of uncertain net value," reports this Lancet meta-analysis.

Why?

This major study shows that although regular use can cut the rate of non-fatal heart attacks, it can also increase the risk of internal bleeding by a third.

Healthy adults who take daily aspirin to prevent heart attacks could be doing more harm than good, warn researchers. The researchers "found that healthy people who take aspirin reduced their already small risk of heart attack or stroke by 12 percent, while the small risk of internal bleeding is increased by a third." This means there were five fewer non-fatal heart attacks for every 10,000 people treated. This pro was was offset by the con of a comparable increase in bleeding -- one extra stroke and three cases of stomach bleeding per 10,000 people treated."

Meanwhile, the secondary prevention studies showed that where patients were taking aspirin to prevent a repeat attack -- aspirin reduced the chances of serious vascular events by about one-fifth and this benefit clearly outweighed the small risk of bleeding.

Older age, male sex, diabetes, and high blood pressure were associated with significantly elevated absolute ischemic stroke and major coronary event risk, but also with significantly increased risk of major extracranial bleeding and at least a trend for hemorrhagic stroke as well.


Please remember, as with all our articles we provide information, not medical advice.
For any treatment of your own medical condition you must visit your local doctor, with or without our article[s]. These articles are not to be taken as individual medical advice.

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