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Rate of inappropriate aspirin use for primary CVD prevention may exceed 10%
Within the National Cardiovascular Disease Registry, the inappropriate aspirin use frequency rate for primary prevention of CVD was 11.6%.
Using data from the National Cardiovascular Disease Registry (NCDR) Practice Innovation and Clinical Excellence registry, researchers examined the frequency and practice-level variations in inappropriate aspirin use for primary prevention in 68,808 patients at 119 centers who received aspirin for primary prevention from January 2008 to June 2013.
Inappropriate aspirin use was defined in accordance with United States Preventive Service Task Force and American Heart Association guidelines: prescription for a patient with 10-year CVD risk less than 6% as determined by the Framingham general CVD risk-assessment tool.
Practice-level variation
Ravi S. Hira, MD, from the section of cardiology of the department of medicine at Baylor College of Medicine, Houston, and colleagues reported significant practice-level variation in appropriate aspirin use (range, 0% to 71.8%; median, 10.1%; interquartile range, 6.4%; adjusted median rate ratio=1.63; 95% CI, 1.47-1.77).
Excluding women aged 65 years and younger, for whom aspirin for primary prevention is not recommended in guidelines, the researchers found that the results remained consistent (inappropriate use frequency, 15.2%; median practice-level inappropriate aspirin use, 13.8%; interquartile range, 8.2%; adjusted median RR=1.61; 95% CI, 1.46-1.75). Results also remained consistent after exclusion of patients with diabetes (inappropriate use frequency, 13.9%; median practice-level inappropriate aspirin use, 12.4%; interquartile range, 7.6%; adjusted median RR=1.55; 95% CI, 1.41-1.67).
Compared with appropriate aspirin use, inappropriate use was more common among younger patients (49.9 years vs. 65.9 years; P<.001) and women (20.3% men vs. 47.4% men; P<.001).
Rates of inappropriate use declined with time, from 14.5% in 2008 to 9.1% in 2013.
Salim S. Virani
“Medical providers must consider whether the potential for bleeding outweighs the potential benefits of aspirin therapy in patients who don’t yet meet the guidelines for prescribing aspirin therapy,” Hira and Salim S. Virani, MD, PhD, also from the section of cardiology of the department of medicine at Baylor College of Medicine, said in a press release. “Since aspirin is available over the counter, patient and public education against using aspirin without a medical provider’s recommendation will also play a key role in avoiding inappropriate use.”
Bleeding risks
In a related editorial, Freek W.A. Verheugt, MD, from Onze Lieve Vrouwe Gasthuis, Radboud University, Nijmegen Medical Centre, Amsterdam, noted that aspirin can be effective in the primary prevention of CVD, but “it is associated, however, with excess extracranial bleeding that, regardless of the baseline risk, seems to come close to its benefit. This limitation of aspirin may be due to other preventive strategies currently applied and used extensively in cardiology practice. Thus, inappropriate use of aspirin should be avoided, especially in the younger patient population.”
For more information:
Hira RS. J Am Coll Cardiol. 2015;65:111-121.
Verheugt FWA. J Am Coll Cardiol. 2015;65:122-124.
Disclosure: Several researchers report financial relationships with pharmaceutical and device companies; see the full study for a list of the relevant financial disclosures. Verheugt reports receiving educational/research grants and honoraria for consultancies and presentations from Bayer Healthcare.
Perspective
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This study reinforces the concept that we are not entirely certain how to use aspirin for the primary prevention of CV events. I think it is quite fascinating that the active ingredient in aspirin has been around for thousands of years; aspirin as a drug has been around for more than a century; and we are still learning how it affects individuals and still understanding the gravity of the potential side effects. This study, in my mind, tells us that there are many patients out there whose benefit-risk profile is not supported in terms of the evidence base.
In the last few years, there has been a lot of attention to this concept. The FDA came out in the past year once again stating that aspirin should not be used in all subjects for the prevention of CV events. The guidelines take a more liberal approach and suggest that there are individuals who would benefit from aspirin for primary prevention. In this study, the researchers looked at very low-risk individuals, with less than 6% risk for a CV event within 10 years, and they still found that a sizable percentage of patients are taking aspirin.
There are important limitations with this study as well. It used the traditional Framingham risk criteria to determine 10-year risk. There are many other algorithms that can tell you an individual’s risk that include components that are not included in the Framingham algorithm. For example, if you are taking care of an individual who has a very strong family history of MI in their 40s, that is not captured in the Framingham algorithm, but it may make sense to use aspirin in that particular person. So there are problems with this analysis, because it only used a single risk score. Nonetheless, the study reinforces the issue that we have to become smart about how we use aspirin.
Complicating matters is that aspirin is an over-the-counter drug, so there are many people who may be taking it not necessarily because their physician told them to, but because they heard from a friend, colleague or family member that they take aspirin and it is a great drug. I don’t know how much of these findings are because of a doctor’s prescription. So doctors should have a discussion with all their patients about all their prescription and OTC medicines and the benefits vs. risks. I think there are significant benefits for aspirin in certain individuals: reduction in the risk for MI, stroke and blood clots. But we also have to remember there is potential very significant harm, such as cerebral hemorrhage. Doctors and patients need to understand the potential benefit and the potential risk, and then determine whether in that particular individual the benefit outweighs the risk.
One thing is missing in this field. When you consider cholesterol-lowering medicine, you measure an individual’s cholesterol to determine whether they should start the drug. When you consider BP-lowering medicine, you measure an individual’s BP to determine whether they should start the drug. It is very interesting, surprising and a little bit sad that when we consider an antiplatelet medicine, we don’t measure how the medicine works. In the future, we will learn how to measure an individual’s platelet function or an individual’s risk for having a platelet-mediated event, and then smartly tailor personalized therapy to that individual based on their risk of their platelets being activated. And then we would target that individual with an antiplatelet drug. I don’t think we are there yet, but I think we are getting there. It is an exciting time for that purpose.