Caution urged on taking daily doses of aspirin for heart benefits
14 November 2013
Researchers at Warwick Medical School have published the most
comprehensive review of the benefits and risks of a daily dose of
prophylactic aspirin. They warn that further research is needed into
the side effects on the gastrointestinal system.
The possible benefits of a daily dose have been promoted as a
primary prevention for people who are currently free of, but at risk
of developing, cardiovascular disease or colorectal cancer.
However, any such benefit needs to be balanced alongside a fuller
understanding of the potentially harmful side effects such as
bleeding and gastrointestinal problems.
The paper, published by the National Institute for Health
Research Health Technology Assessment (NIHR HTA) Programme, reviews
the wealth of available randomised controlled trials (RCTs),
systematic reviews and meta-analyses, allowing the team from Warwick
Evidence to quantify those relative benefits and risks.
The reported benefits of taking aspirin each day ranged from 10%
reduction in major cardiovascular events to a 15% drop in total
coronary heart disease. In real terms, that would ultimately mean
33-46 fewer deaths per 100,000 patients taking the treatment.
There was also evidence of a reported reduction in incidents of
colorectal cancer, which showed from approximately five years after
the start of treatment. This would equate to 34 fewer deaths from
colorectal cancer per 100,000 patients.
The adverse effects of aspirin were also noted with a 37%
increase in gastrointestinal bleeding (an extra 68-117 occurrences
per 100,000 patients) and between a 32-38% increase in the
likelihood of a haemorrhagic stroke (an extra 8-10 occurrences per
Aileen Clarke, Professor of Public Health Research and Director
of Warwick Evidence at Warwick Medical School, said, “This study
looks deeper into the range of research on regular aspirin use than
anything before, using more innovative methods, and it makes it
clear that there is an incredibly fine balance between the possible
benefits and risks of the intervention. We need to be extremely
careful about over-promoting aspirin intervention without having
first fully understood these negative side effects.
“There are a number of ongoing trials that will be completed in
the coming six years which may help to clarify this further,
including the impact of different dose regimens.”
See the National Institute for Health Research Health Technology
Assessment (NIHR HTA) Programme:
HTA - 11/130/02: Aspirin for
prophylactic use in the primary prevention of cardiovascular disease
and cancer. A systematic review and overview of reviews.