Aspirin may not be the answer to lowering the risk of heart disease
Daily aspirin has been considered to be beneficial in reducing the risks of heart disease and cancer. However, potential benefits must be balanced against the possible harm from side effects, such as bleeding and gastrointestinal (GI) symptoms. It is particularly important to know the risk of side effects when aspirin is used as primary prevention that is when used by people as yet free of, but at risk of developing, cardiovascular disease (CVD) or cancer, according to a new study.
Professor Alieen Clarke, MD, FRCGP, FFPH, Professor of Public Health Research, Director of Warwick Evidence and Acting Director of Division of Health Sciences, leader of study and colleagues set out to identify randomized controlled trials, systematic reviews and meta-analyses of RCTs of the prophylactic use of aspirin in primary prevention of CVD or cancer.
In total, 2572 potentially relevant papers were identified and 27 met the inclusion criteria.
The result showed benefits of aspirin ranged from 6% reduction in relative risk for all-cause mortality and a 10% reduction in major cardiovascular events and a 15% reduction in total coronary heart disease.
Reductions in cancer mortality ranged from 0.76 and 0.93. Inclusion of the Women's Health Study changed the estimated odds ratios changed to 0.82 to 0.97.
Reported increase relative risk of adverse events from aspirin use was 37% for GI bleeding, 62% for major bleeds and 38% for hemorrhagic stroke. Estimates of absolute rates of harm from aspirin use, per 100,000 patient-years of follow-up, were 99-178 for non-trivial bleeds, 46-49 for major bleeds, 68-117 for GI bleeds and 8-10 for hemorrhagic stroke. Meta-analyses aimed at judging risk of bleed according to sex and in individuals with diabetes were insufficiently powered for firm conclusions to be drawn.
In their conclusion the team writes “We have found that there is a fine balance between benefits and risks from regular aspirin use in primary prevention of CVD. Effects on cancer prevention have a long lead time and are at present reliant on post hoc analyses. All absolute effects are relatively small compared with the burden of these diseases. Several potentially relevant ongoing trials will be completed between 2013 and 2019, which may clarify the extent of benefit of aspirin in reducing cancer incidence and mortality. Future research considerations include expanding the use of IPD meta-analysis of RCTs by pooling data from available studies and investigating the impact of different dose regimens on cardiovascular and cancer outcomes.”
Professor Clarke related to BBC News "It would be lovely to say over-50s should take an aspirin a day and have much less cancer, but the research hasn't yet been done and we should be cautious.” “We need to be extremely careful about over-promoting aspirin."
Aspirin reduces the elderly’s increased risk for heart disease by thinning the blood, making it less likely to clot inside veins and arteries. Blood-thinners also reduce the rate of stroke.
Amy Thompson, senior cardiac nurse at the British Heart Foundation commented "Aspirin is extremely important for many heart patients, but for people free of heart disease the jury is still out as the risks are likely to outweigh the benefits.”
According to the CDC, heart disease is the leading cause of death for both men and women.
Who should take daily aspirin? According to the Mayo Clinic your doctor may recommend aspirin therapy if:
You've already had a heart attack or stroke
You haven't had a heart attack, but you have had a stent placed in a coronary artery, have had coronary bypass surgery, or you have chest pain due to coronary artery disease (angina)
You've never had a heart attack, but you're at high risk of having one
You're a man with diabetes older than 50, or a woman with diabetes older than 60
This study appears in the journal Health Technology Assessment