17 Sep Some Adults Without Heart Disease May Benefit From Aspirin

MedicalResearch.com Interview with:

Dr. Vanessa Selak

Dr Vanessa Selak MBChB, MPH (Hons), PhD, FAFPHM, FNZCPHM
Senior Lecturer in the Section of Epidemiology & Biostatistics
School of Population Health, Faculty of Medical and Health Sciences
University of Auckland

MedicalResearch.com: What is the background for this study?

Response: For people who have already had a cardiovascular event, the benefits of aspirin generally outweigh its harms but the balance of benefits and risks is unclear in primary prevention. It was hoped that the results of three major trials published last year would determine whether or not aspirin had a role in the primary prevention of cardiovascular disease (CVD) among people at intermediate risk of CVD, but these trials recruited participants at lower CVD risk than expected. An updated meta-analysis of aspirin for the primary prevention of CVD, which incorporated the findings from these three trials, has confirmed that aspirin reduces the relative risk of CVD and increases the relative risk of bleeding.

We investigated, using an individualized assessment of the absolute cardiovascular benefits of aspirin and its bleeding harms among New Zealand adults aged 30-79 years without established CVD who had their CVD risk assessed in primary care between 2012 and 2016, whether there are individuals without established CVD for whom the absolute cardiovascular benefits of aspirin are likely to outweigh its absolute bleeding harms.

MedicalResearch.com: What are the main findings? 

Response: We found that 2.5% of women and 12.1% of men were likely to experience net benefit from treatment with aspirin for 5 years when one CVD event was assumed to be equivalent in severity to one major bleed, increasing to 21.4% of women and 40.7% of men when one CVD event was assumed to be equivalent to two major bleeds. Net benefit subgroups had higher baseline CVD risk, higher levels of most established CVD risk factors and lower levels of bleeding-specific risk factors than net harm subgroups. Among the net benefit subgroups there was a considerable range in pre-treatment CVD and bleeding risks, whether one CVD was assumed to be equivalent to one or two bleeding events.  

MedicalResearch.com: What should readers take away from your report?

Response: There are individuals without CVD for whom aspirin is likely to result in net benefit. It would be difficult to identify these people based on a threshold of CVD risk (above which net benefit from aspirin is likely) or bleeding risk (above which net harm from aspirin is likely), given the considerable range in pre-treatment CVD and bleeding risks among people in whom net benefit (and net harm) were likely. Instead, identification of individuals likely to benefit from aspirin for the primary prevention of CVD requires a personalised assessment of the benefits (number of CVD events avoided) and harms (number of major bleeds caused) of aspirin.

We have developed a web-based calculator (https://aspirinbenefitharmcalculator.shinyapps.io/calculator/) that provides physicians with individualised estimates of the benefits and harms of aspirin for New Zealand patients. This calculator can be used to support physicians in their discussions with patients who will ultimately need to decide whether or not to take aspirin for the primary prevention of CVD. 

MedicalResearch.com: What recommendations do you have for future research as a result of this work?

Response: Similar calculators could be developed for non-New Zealand populations, but would require both prognostic CVD and bleeding risk equations suitable for use in those populations.

MedicalResearch.com: Is there anything else you would like to add?

Response: The limitations of this study are that there is uncertainty in the risk scores and effect estimates; the effects of aspirin on cancer outcomes were not considered; and the applicability to non-New Zealand populations was not assessed. 

Citation: Personalized Prediction of Cardiovascular Benefits and Bleeding Harms From Aspirin for Primary Prevention A Benefit–Harm Analysis

Vanessa Selak, MBChB, PhD; Rod Jackson, MBChB, PhD; Katrina Poppe, PhD; Billy Wu, MPH; Matire Harwood, MBChB, PhD; Corina Grey, MBChB, PhD; Romana Pylypchuk, PhD; Suneela Mehta, MBChB, MPH; Yeun-Hyang Choi, MSc; Andrew Kerr, MBChB, MD; Sue Wells, MBChB, PhD

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Last Updated on September 17, 2019 by Marie Benz MD FAAD