Aspirin for prevention of cardiovascular disease “ineffective or even harmful in the majority of patients” (just like statins)

Aspirin is perhaps best known for its painkilling properties. But another of its actions in the body is to inhibit the ability of blood components called ‘platelets’ to stick together. It’s when platelets clump together that clots are formed. In other words, aspirin partially inhibits clot formation. Small blood clots called ‘trombi’ are essentially responsible for the blocking off of arteries that can cause heart attacks and strokes. For this reason, many individuals are advised to take aspirin regularly to help prevent these ‘cardiovascular’ events.

However, there has in recent times been some challenge to the conventional wisdom on aspirin. There has been growing awareness that many people need to be treated with aspirin for one to benefit as well the fact that aspirin can cause side-effects (like bleeding in the gut) that can be extremely hazardous and even fatal, particularly in the elderly. The ardour that the medical profession once had for aspirin has cooled of late.

Further dampening of the enthusiasm is likely to come as a result of a recent study which looked at the impact of aspirin taking in women [I]. The women in this study were essentially ‘healthy’ in that they had no history of heart attack or stroke. In medicine, prevention in this type of person is described as ‘primary prevention’. Basically, the researchers found some benefit for older women over the age of 65. However, in this group (generally deemed to be a elevated risk), it was calculated that 50 women would have be treated with aspirin for 10 years to prevent one ‘cardiovascular event’ (e.g. a heart attack or stroke). In other words, 49 people would take aspirin for 10 years with no benefit at all. And let’s not forget there is a risk of side-effects too.

For younger women, overall benefits were even less likely. The authors of this study concluded that: “Aspirin was ineffective or even harmful in the majority of patients.” These findings are in keeping with contemporary research on aspirin, so we should not be too surprised by them.

However, I had another sense of deja vu reading about this study, in that it brought back to me the evidence base regarding the ‘effectiveness’ of cholesterol-reducing statins. Here’s some stuff we know about the effectiveness of these drugs:

  • In primary prevention, statins do not reduce the risk of death [2]
  • In predominantly primary prevention, in women of any age, there is no reduced risk of cardiovascular events with statin treatment [3].
  • This is also true for men aged 70 or over [3].
  • In high-risk men aged 30-69 years, about 50 patients need to be treated for 5 years to prevent one cardiovascular event [3].

And this is before we even start to factor in potential side-effects such as liver damage, muscle pain and weakness and kidney failure.

What is it about ‘preventive medicine’ that makes it so utterly useless at prevention? One problem, I think, is that it almost certainly fails to address the true underlying causes of illness. Heart disease and strokes are not the result of deficiencies in either aspirin or statins, after all, and in this sense are unlikely to strike at the heart of the processes that drive disease.

Some people say you could make the same point regarding this ‘pill for an ill’ philosophy could be made for more natural medicine too. Maybe, though the difference here is that cardiovascular disease might actually be promoted through a deficiency of, say, omega-3 fats or vitamin D, and upping levels of these substances in the body, even from a pill, may indeed have real value in terms of disease prevention. Also, as these things are innate to the body (which things like aspirin and statins are not), the potential for adverse effects is much smaller too.

References:

1. Dorresteijn JA, Aspirin for primary prevention of vascular events in women: individualized prediction of treatment effects. Eur Heart J 16 November 2011 [Epub ahead of print]

2. Ray KK, et at. Statins and all-cause mortality in high-risk primary prevention: a meta-analysis of 11 randomized controlled trials involving 65 229 participants. Arch Intern Med. 2010;170(12):1024-1031

3. Abramson J, et al. Are lipid-lowering guidelines evidence-based? The Lancet 2007:369:168-169

16 Responses to Aspirin for prevention of cardiovascular disease “ineffective or even harmful in the majority of patients” (just like statins)

  1. Kris 1 December 2011 at 6:01 pm #

    Great article.

    I’m going to keep those statin studies at hand when I start pharmacology next year (3rd year of med school) and I’m going to show them to the teacher and my fellow students.

    Although I’ve noticed that in my country (Iceland) the doctors and professors are generally open-minded and non-corrupt.

    The health care system here is so much better than for example in the USA where some health professionals and the pharmaceutical industry literally profit from keeping people sick.

  2. Bill 2 December 2011 at 12:56 am #

    Low dose aspirin does seem to make my blood thinner as I bleed more freely when I cut myself now.
    Would this not make it easier for my heart to pump blood around my body and improve symptoms of angina?

  3. JeffBland 2 December 2011 at 8:18 pm #

    @Michael,

    Keep up the good work.

  4. frank weir 2 December 2011 at 9:59 pm #

    @Michael. Thanks for your input. I see a physician who is part of the University of Michigan health system and it seem to me that the big institutions take a look at research and then develop standards of care that are followed. They are loath to deviate partially because of medical malpractice lawsuits I suspect. It is discouraging for me as a type 2 diabetic since my doctor insists that I should be eating more whole grains AND that there is simply no way that Simvastatin could have cause a recent neuropathy I had in my right leg even though I have normalized my blood glucose by diet and lost 30 pounds. I sense that if any kind of suggestion would deviate from the institutional standards of care, then they just aren’t considered. I see admittedly anecdotal evidence, and even some hard research that seems to indicate statins can cause neuropathies. My doctor flatly said there was no way, end of discussion. One of my concerns is the state of medical research which I understand is often financed by pharmaceutical companies and results sometimes are not properly revealed as we saw with Vioxx and Avandia. I wonder how the big medical institutions come to configure their standards of care and how carefully do they evaluate research results before deciding what doctors will do in the treatment room?

  5. Donald Tiso 2 December 2011 at 10:11 pm #

    I would be very interested in Dr John’s view on whether a short course of low dose asprin is likely to be beneficial in reducing the risk of DVT during and after plane travel , that’s the only time I presently take asprin

  6. Pete Grist 2 December 2011 at 10:23 pm #

    Michael
    Good post. The implication that doctors as a group are corrupt gets us nowhere. Science is never an absolute, but a voyage of theories surviving until a better one comes along. Which is of course the difficulty, distinguishing that which agrees with you current world view from something better that might challenge it!

  7. Michael 3 December 2011 at 2:15 am #

    @Kris – I’m sorry, but I cannot let your comment go…. as a 3rd year medical student, I cannot really rely on the fact that you know for a fact that the “majority of doctors … are generally open-minded and non-corrupt”. Generalizations are a fatal flaw unless backed by real data.

    I am a physician in the USA (@25y) and take issue that the medical system in Iceland is “so much better” then here.

    Lets just stick to the issue at hand and leave this type of bloviating out of it…

    PS: As an Emergency Physician who is working towards opening a Functional Medicine practice, I fully appreciate the clash between those who believe and use functional medicine and those who do not. I have NEVER felt my traditional colleagues were intentionally “keeping people sick” to profit blah blah blah… They are, at worst, ill informed or practicing as per their comfort level. Part of my “job” is to help other physicians understand the alternate approach to patient care that is Function Medicine… all of us have to move Functional Medicine forward through evidence and good science – something I plan to work on for the remainder of my professional life…

  8. DanC 3 December 2011 at 8:12 am #

    Preventive Medicine: A thorn in the side of the medical-pharmaceutical-insurance complex (in the USA).

  9. Deborah Booth 3 December 2011 at 7:51 pm #

    Yes John, please comment on aspirin before during and after plane travel, especially long haul…

  10. Susan 4 December 2011 at 2:08 am #

    I have tinnitus that is aggravated if I take aspirin. A PA told me that, that years ago, the ringing in the ears is one of the ways that was used to do dose aspirin. At one point, my tinnitus was so bad that I could not even hear my own thoughts. That particular PA was the one who originally had me on aspirin for my tinnitus! When I quit taking the aspirin my tinnitus subsided substantially.

  11. John Briffa 4 December 2011 at 4:33 pm #

    Donald and Deborah

    As long as there are no contraindications, I’d see using aspirin around the time of air travel (especially long haul) as a perfectly reasonable thing to do.

  12. Angela 4 December 2011 at 5:06 pm #

    According to Wikipedia, long-term aspirin use eventually does permanent damage to the body’s blood-clotting abilities. Anyone know if this is true?

  13. J.A. McCall 4 December 2011 at 9:31 pm #

    The biggest problem that most doctors have with aspirin is because it does work.

    My mother in law died at 42 of a stroke. My father in law died of cancer of the sweetbread at 62.

    I figured online what the life expectancy of my husband and his siblings is by filling in personal info. According to the test they should all be dead if you take into account their parents. The difference is probably because they each take an aspirin a day and each take generic blood pressure medicine. They are 68, 70, and 72 years old.

  14. majkinetor 12 December 2011 at 8:22 pm #

    Chronic aspirin causes GI tract bleeding and vitamin C deficiency. That is the reason pharma invented cox-2 selective inhibitors. There is nothing wrong with acute aspirin.

    Better use fish oil instead.

  15. Nathan 13 December 2011 at 12:26 pm #

    Heavy aspirin use is one of the main clinical causes of tinnitus, as you mentioned, Susan. Aspirin is cheap, genericized, and when taken in low-dose pill as maintenance is one of the best ways to prevent coronary events, especially with previously diagnosed coronary disease. That research is extremely well documented and supported. While aspirin may not be indicated in healthy, younger patients, that’s hardly anything new.

    The standard of administration for any drug is treatment only when benefits outweigh side effects – for aspirin, there are clear, significant benefits in preventing events in high-risk patients and those with known disease. None of these studies or analyses call that into question, unlike the misleading, sensationalistic title of this article.

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