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Friday, October 19, 2018

Changing status for use of aspirin in primary prevention of heart disease

In the not too distant past based in part  on the results of the Physicians Health Study (1989) and the Women's Health Study (2005) it seemed reasonable to recommend aspirin for cardiovascular disease prevention. Recommendations were typically based on various guidelines that were estimates of a person's risk based on various risk factors such as cholesterol level,Blood pressure, smoking status, family history, etc. Since age is a major risk factor many of elderly are taking low dose aspirin with or without a physicians's advice.Is that still a good idea?

Dr. Paul Ridker in an editorial in the NEJM (1) questions whether the old advice is still justified in light of more recent clinical trial data  and perhaps a changing risk baseline for the population in general. More people now are on medication for blood pressure,fewer smoke and many more now are taking statin drugs than they were at the times of the PHS and WHS.

In the same issue of NEJM 3 primary prevention trials were published. Only the trial in diabetic patients (the ASCEND trial) was there shown to be a statistically signficiant reduction in vascular events with asprin. A 12% reduction is vascular events was countered by a 29% increase in major bleeding and the all-cause mortality was the same in the control and the treatment groups.

The ARRIVE trial was  a primary prevention trial in"high risk " subjects The intention-to-treat analysis showed that the primary outcome was the same in the control and aspirin groups. The primary outcome was a composite of stroke,heart attack,unstable angina,TIAs and death from CV causes.Gi bleeding was twice as common in the aspirin group.

The ASPREE trial was a primary prevention trial in subjects 70 years of age and older who were free of CV disease ,dementia or disability on entry into the study. After five years of 100 mg aspirin a day versus placebo there was no CV benefit .There was more GI bleeding with aspirin ( Hazard ratio of 1.39).

So unlike aspirin's well established  role in secondary CV disease prevention the benefit-risk ratio in primary prevention is ( in Ridker's words) "exceptionally small" . Dr. Ridker has been an advocate of statin use and it is not surprising  that he ends his commentary with: "Thus beyond diet maintenance,exercise, and smoking cessation,the best strategy for the use of aspirin in the primary prevention of cardiovascular disease may simply be to prescribe a statin instead."

1) Ridker, PM Should Aspirin be used for primary prevention in the post-statin era? NEJM 379;16 oct 18 2018. 1572

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