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Major bleeding may be more common than previously thought among people without cardiovascular disease (CVD) who are not on antiplatelets, a prospective cohort study suggested.

The proportion of a large community cohort of New Zealanders, ages 30-79, (n=359,166) experiencing a first major bleeding event leading to death or hospitalization was 1.1% overall over a median follow-up of 2.8 years. That risk dipped slightly to 0.9% among lower-risk individuals without medical conditions associated with increased bleeding and 0.9% in those not taking medications that increase bleeding risk, reported Vanessa Selak, PhD, of University of Auckland, and colleagues.

GI bleeding made up more than 70% of these events, they wrote in the . The risk of nonfatal GI tract bleeding varied according by group and was estimated to be:

• Overall: 2.19 per 1,000 person-years (95% CI 2.11-2.27)
• Patients with lower risk: 1.77 per 1,000 person-years (95% CI 1.69-1.85)
• Individuals off medications that increase bleeding risk: 1.61 per 1,000 person-years (95% CI 1.52-1.69)

GI tract bleeding-related case fatalities also reached 3.4%, 4.0%, and 4.6% of these groups, respectively.

"The risk of a nonfatal GI bleeding event and case fatality associated with GI bleeding among people without CVD who were not receiving antiplatelet therapy were both higher in this study compared with estimates derived by the USPSTF [U.S. Preventive Services Task Force] for their recommendations on use of aspirin for primary prevention of CVD and colorectal cancer," Selak's group noted.

Overall, rates for bleeding and death seen in the current study exceeded USPSTF estimates by margins ranging from 50% to more than 300% in some lower-risk groups.

Non-fatal bleeding risk in the New Zealanders was higher than the corresponding estimates by the USPSTF in every age- and sex-specific category, the difference being greatest in people age 40-49. However, the difference grew smaller after excluding higher-risk individuals and those taking medications that increased the risk of bleeding.

On the other hand, there was more case fatality associated with GI bleeding in this study than the USPSTF had estimated, and this was evident across all age groups in both men and women, and was not attenuated in the lower-risk and non-medication cohorts.

"The role of aspirin in primary prevention of cardiovascular disease remains uncertain, and the current study adds to this uncertainty by showing higher than previously assumed bleeding rates," commented Roxana Mehran, MD, of the Icahn School of Medicine at Mount Sinai in New York City, who was not involved in the analysis.

And even though these data may not be directly applicable to interventional cardiology trials, what the study does is it highlights the importance of accurately determining bleeding rates, she told 麻豆传媒, which is "very important because several analyses have shown that bleeding events are associated with at least the same, if not a higher risk for mortality compared with ischemic cardiovascular events."

The study included patients who had a primary care visit in New Zealand in 2002-2015 with a CVD risk assessment recorded in PREDICT, a web-based, EHR-integrated decision support program. Mean age was 54. Women accounted for 44% of the study population, and those of European ethnicity 57%.

The risk of a nonfatal bleeding event generally increased with age no matter the sex of the patient. Additionally, compared with women, men were at greater risk of nonfatal bleeds.

One major limitation of the analysis was the availability of over-the-counter aspirin, a potential confounder of the results.

Nonetheless, the study suggests that the net benefit of aspirin for primary prevention is lower than that estimated by the USPSTF, according to the authors. "As noted by the USPSTF, there is a paucity of data on absolute bleeding risk from community cohorts, and this is the first large-scale study that, to our knowledge, that has directly measured the risk of major bleeding by sex and age group in a contemporary community cohort of people without CVD and not receiving antiplatelet therapy."

"This study presents age- and sex-specific data, which could support the development of population-level guidelines," they said. "However, validated risk algorithms are required to take into account multiple risk factors at the same time, as with CVD itself, among people without CVD, to optimize the individualized assessment of the balance of absolute benefits and harms of aspirin for primary prevention of CVD."

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