Review of daily aspirin dosage highlights concerns about side effects
Researchers at Warwick Medical School have published the most comprehensive review of the benefits and risks of a daily dose of prophylactic aspirin and warn that greater understanding of side effects is needed.
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 100,000 patients)
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.”
Warwick Evidence, part of the Division of Health Sciences at Warwick Medical School, assesses primary research on behalf of the NIHR HTA Programme.
The full study is available online here: http://www.journalslibrary.nihr.ac.uk/hta/volume-17/issue-43
The National Institute for Health Research Health Technology Assessment (NIHR HTA) Programme funds research about the effectiveness, costs, and broader impact of health technologies for those who use, manage and provide care in the NHS. It is the largest NIHR programme and publishes the results of its research in the Health Technology Assessment journal, with over 600 issues published to date. The journal’s 2011 Impact Factor (4.255) ranked it in the top 10% of medical and health-related journals. All issues are available for download, free of charge, from the website. The HTA Programme is funded by the NIHR, with contributions from the CSO in Scotland, NISCHR in Wales, and the HSC R&D Division, Public Health Agency in Northern Ireland.www.hta.ac.uk.
The National Institute for Health Research (NIHR) is funded by the Department of Health to improve the health and wealth of the nation through research. Since its establishment in April 2006, the NIHR has transformed research in the NHS. It has increased the volume of applied health research for the benefit of patients and the public, driven faster translation of basic science discoveries into tangible benefits for patients and the economy, and developed and supported the people who conduct and contribute to applied health research. The NIHR plays a key role in the Government’s strategy for economic growth, attracting investment by the life-sciences industries through its world-class infrastructure for health research. Together, the NIHR people, programmes, centres of excellence and systems represent the most integrated health research system in the world. For further information, visit the NIHR website (www.nihr.ac.uk).
This article presents independent research funded by the National Institute for Health Research (NIHR). The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health.