Archive for the ‘aspirin use’ Category

Should I be taking aspirin?

Wednesday, January 30th, 2013

I take a dose equivalent to 1/4 tablet of aspirin

One of our friends recently told my wife she'd stopped taking aspirin after a news report linked regular use of the medication to macular degeneration. We've both taken 81 mg of aspirin a day and, after I'd heard that people may not absorb the enteric coated form well (and I couldn't find any other form in that size at the local drugstore), I'd ordered ten bottles of chewable orange-flavored aspirin online from Amazon.

Then I decided to read the medical reports that our friend's recommendation had been based on. She doesn't have a medical background and hadn't looked at the original data, but instead had seen a warning in a newspaper article. Let's start at The New York Times blog. On Dec 12, 2012 they published an article by Anahad O'Conner titled "Aspirin Tied To Rare Eye Disorder."

It's a very well-worded article written by a 31-year-old, Yale-educated Times reporter who writes a weekly science column and has published two books He notes the article he based his piece on was from JAMA with the lead author, Dr. Barbara Klein, being a professor of ophthalmology at the University of Wisconsin, Madison. Since I'm a UW graduate (BS 1963, MD 1966), I was particularly interested in her study.

It used data from the Beaver Dam Eye Study, started in 1988-1990 and concluded in 2010. O'Connor very appropriately noted this was an observational study, not a prospective, controlled research project. In other words a group of ~5,000, aged 43 to 84, agreed to have regular eye exams and reports were published after the 5-, 10-, 15- and 20-year followups.More than 300 publications have resulted from this project with data supporting a relationship of cataracts and age-related macular degeneration (AMD) to cigarette smoking.

Klein's paper stated that an estimated 19.3% of US adults take aspirin on a regular basis. It's commonly recommended for anyone who has had a heart attack (secondary prevention), but many   of us who've never had evidence of coronary vascular disease also take aspirin. This is primary prevention and is controversial with some data suggesting reduction of heart attacks in men over 45, but not women, although they may have a 17% reduction in stroke incidence.

A senior who has AMD may need a magnifying glass.

A January 21,2013 article from an Australian group reported a two-fold increase in AMD of a particular type, independent of smoking habits. Nearly a quarter of regular long-term aspirin users developed neovascular AMD, two and a half times the percentage of those who did not regularly take aspirin.

A 2001 paper in the Archives of Ophthalmology reported a randomized, double-masked, placebo-controlled study of low dose aspirin (one adult tablet every other day) plus 50 milligrams of beta carotene (a vitamin A precursor rated possibly effective in treating advanced AMD) among over 20,000 US male physicians aged 30 to 84 in 1982. The study was stopped after ~5 years due to a statistically extreme reduction (44%) in first heart attacks. There were fewer cases of AMD in those taking low-dose aspirin than in those who got the placebo.

There's also some data supporting aspirin's role in cancer prevention, especially in malignancies of the colon. Here the benefit was unrelated to aspirin dose (75 mg/day and up), but increased with age.

So let me look at my own risks: my dad had a large polyp in the earliest part of the colon, an area hard to see even on colonoscopy. It was initially felt to be benign, but later had some areas of low-grade malignancy. He also had macular degeneration in his remaining eye  diagnosed at age 90+ (the other eye having been removed nearly sixty years previously after a bad cut and a subsequent infection). My brother died of a heart attack at age 57 and my mother had a heart attack at age 74 with a cardiac arrest; (Dad resuscitated her and she lived to age 90).

The editorial that accompanied the recent JAMA article is thoughtful and impressive. Its title was "Relationship of Aspirin Use With Age-Related Macular Degeneration: Association or Causation?" and it concludes "From a purely science-of-medicine perspective, the strength of evidence is not sufficiently robust to be clinically directive." It then switches to a different viewpoint, the art-of-medicine perspective, saying maintaining the status quo is currently the most prudent approach, especially in secondary prevention (someone who has already had a cardiovascular event). For those of us who haven't, the risks versus benefits should be individualized based on our own medical history and value judgement.

I'm going to discuss this with my own physician but not stop taking a chewable 81 mg aspirin daily until I do.

Aspirin revisited

Sunday, June 10th, 2012

They may be good for your heart, but.....

Some years ago I began to take a baby aspirin a day as a cardiovascular event preventive medication. In my case, it was primary prevention. I've not had a cardiovascular event and don't have major risk factors. Most of my relative lived until their 90s; the only exception was my older brother who smoked three packs of cigarettes a day, gained 50+ pounds after age 40, didn't always take his blood pressure meds and loved foods that I don't consider as "heart-healthy/" When he died of a heart attack at age 57, I couldn't find his car; Dad said, "Look in the parking lot of the closest Kentucky Fried Chicken," and that's where it was.

Now I plan to stop my daily 81 milligram aspirin having read an article in JAMA which studied the incidence of major bleeding episodes (mostly in the brain or in the bowel) of over 185 thousand people who were taking low-dose aspirin compared to carefully matched controls who weren't.

The authors started with a 4.1 million population base in Italy where aspirin taken to prevent cardiovascular events is paid for by a government prescription plan for all at high risk. A six-year period was selected (start of 2003 to the end of 2008) and those over the age of 30 who began taking low-dose aspirin during that time frame were the study subjects. There were nearly 600,000 people considered for the study, but after appropriate exclusions just under a quarter million current aspirin users were carefully matched with control subjects. From a random sample of nearly 850,00 non-aspirin users, matches were found for 186,425.

let's look at the statistics

I was impressed by the thoroughness of the statistical procedure using propensity scores  ( a way to get apples matched with apples, not with zebras or even melons) and a "greedy-matching algorithm" (this link is only for math fiends) as another way to reduce bias. The results convinced me to stop taking my baby aspirin a day. The number of study subjects who had their first major bleed was fairly low (6,907  or 1.85% of all those in the study were hospitalized for a hemorrhagic event) and the absolute difference between aspirin users and controls weren't huge  (5.58 per 1,000 person-years for those taking the drug versus 3.60 per 1,000 person-years in those who didn't take aspirin). But those numbers don't tell the whole story.

Men had considerably more bleeding episodes than women and older subjects had increased rates than younger ones. So as a 71-year-old man, I paid attention. I'm not diabetic, but noted that those who were had a higher risk of bleeding whether they took aspirin or not.

This wasn't a randomized controlled study, but its enormous size and careful methods were striking. The accompanying editorial by an MD, PhD from a university in Vienna looked at previous meta-analyses (lumped-together studies) and said that for a hypothetical large group of patents who took low-dose aspirin for secondary prevention, there was a 6 to 1 benefit-risk ratio. That supports giving the drug to people at high risk of a cardiovascular event.

But when you come to primary prevention, a similar large group of 10,000 could be expected to have 7 fewer cardiovascular events at the cost of 1 major bleed in the brain and 3 elsewhere. The odds are low enough that new guidelines in Europe don't recommend giving aspirin for primary prevention. This new study would certainly support that viewpoint.

I crossed off aspirin on my pill calendar.