Aspirin Self-Prescribing Persists in Primary CVD Prevention

Shelley Wood

March 28, 2013

CALGARY, Alberta — Faith in the adapted adage "an aspirin a day keeps the doctor away" remains a key driver of aspirin use in the setting of primary prevention, according to a recent patient survey[1].

Among patients in the waiting rooms of two primary practice clinics in Alberta, Canada almost 40% said they were taking ASA regularly, mostly for prevention of CV events. Of these, only 47% were taking the drug for secondary CVD prevention, while 53% were taking it for prevention of a first CV event.

Moreover, one-quarter of patients taking aspirin for primary prevention said the decision to start taking it was their own, not their doctors.

"We're not saying that nobody should be having aspirin for primary prevention, but after 20 years of evidence [showing little to no benefit and possible harm] of aspirin in primary CV prevention, we believe the decision to take aspirin for primary prevention is something you should discuss with your doctor," Dr Michael Kolber (University of Alberta, Edmonton) told heartwire . "We hypothesize that most of the patients in our primary care clinics are at low risk for CV events, so the risk of preventing a first event is likely offset by the risk of bleeding and other problems."

Changing Guidance on Aspirin in Primary Prevention

Professional societies now discourage aspirin in people with no underlying CVD, in the wake of a number of large studies showing an unfavorable risk/benefit profile in patients with no CV disease. And while that message has been slow to reach cardiologists, it's been even slower to reach primary care physicians and their patients.

"The patients that a cardiologist sees and the patients that a primary care physician or frontline healthcare provider sees are different kinds of patients," Kolber, himself a primary care physician, points out. "We see a lot of relatively healthy people, and by nature of the referral process, cardiologists see everyone with disease."

In all, 906 patients were invited to take the survey in one urban and one rural family medicine clinic; 807 patients completed the survey. Roughly 30% of patients had preexisting cardiac disease. Older patients (70–79 years) were more likely to report taking aspirin compared with patients in the 50–59-year-old age group, and men were more likely to be taking aspirin than women. Aspirin use was similar between the urban and rural respondents.

One of the more striking findings, however, was that 67% of patients taking aspirin said they were advised to do so by their family physician, and family physicians were just as likely to prescribe aspirin for primary prevention as for secondary. Of note, however, specialists also recommended aspirin for primary prevention in 8.5% of cases and 25.4% of secondary prevention patients.

Among patients who decided on their own accord to start taking aspirin, 26.4% of those did so for primary prevention, as opposed to just 3.5% of those who initiated ASA for secondary prevention.

Missing the Boat?

Kolber thinks that the amount of aspirin being prescribed is not the problem; it's a question of who is getting it. "It is likely that many patients of relatively low CV risk are taking ASA for primary CV prevention, while many of those who might benefit from ASA for secondary prevention are not taking it," the authors note. "We're actually missing the boat," Kolber told heartwire .

In another interesting finding, patients taking aspirin were much more likely to say that they believed the benefits of aspirin outweigh its risks, whereas those not taking aspirin were more likely to respond that they were unsure whether the benefits outweigh the risks. Of note, very few patients--whether they were taking aspirin or not--said they believed the potential risks might outweigh the potential benefits.

Kolber says physicians need to do a better job of educating patients, but this means they themselves need to accept that aspirin, for most patients, no longer has a place in primary CVD prevention.

"Part of it is habit. I used to say in the 90s, when you hit 50, just take an aspirin. And we had a generation of physicians who were on it themselves who didn't have an event and think that's a reason to take it. But maybe they were never going to have an event in the first place."


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