Saturday, 11 December 2010

Absolute Risks for each year aspirin taken: major gastrointestinal bleed = 1 in 850; brain haemorrhage = 1 in 3,300

reposted from: Irish Times

What about the risks of unwanted bleeding in people taking aspirin? There is a small but definite risk that aspirin can cause bleeding, especially in the gut. If you have had a gastric or duodenal ulcer in the past, then the risk of a bleed from the stomach is higher. 

For every 850 or so patients treated with aspirin for a year, one person will experience a major gastrointestinal bleed. Aspirin is estimated to cause one additional brain haemorrhage for every 3,300 people who take the drug for a year.

Can you summarise the health benefits of aspirin? The range of benefits attributable to aspirin continue to grow, leading some to label it a “superdrug” this week. As well as lowering deaths from a range of common “solid” cancers, aspirin saves lives in those with established cardiovascular disease. There is some evidence aspirin may help to prevent dementia, which would certainly make sense in cases where the dementia was the result of a series of mini-strokes. And of course it remains a good treatment for fever in adults, as well as an effective anti-inflammatory drug for people with arthritis.

crabsallover highlights in blue, comments in green.

crabsallover says "Absolute Risks for each year aspirin is taken: major gastrointestinal bleed = 1 in 850; brain haemorrhage = 1 in 3,300. Therefore over 10 years taking aspirin daily, the risks are: major gastrointestinal bleed = 1 in 85; brain haemorrhage = 1 in 330. These risks of aspirin use should be offset by the benefits of cancer reduction (21% according to Peter Rothwell et al) with daily aspirin. 

Cancer is a leading cause of death according to WHO who say that cancer accounted for 7.4 million deaths (around 13% of all deaths) in 2004. Therefore total number deaths worldwide from all causes was 57 million when world population was 6.5 billion in 2004. The total chances of dying from all causes is 1 in 114 in any one year (1 in 11.4 over 10 years). The chance of dying from cancer is 1 in 878 in any one year (1 in 87.8 over 10 years). 

So the chances over 10 years of dying from cancer (1 in 87.8) can be compared to chances of a  major gastrointestinal bleed (1 in 85) over the same period. With aspirin the chances of dying from cancer are reduced by 21% so the 1 in 87.8 chance of dying from cancer over 10 years becomes a 1 in 105 chance, a 1 in 17 improvement.

My reasoning probably needs re-working and shows the difficulties of comparing absolute risks!

For all men in the UK the cumulative life time risk of lung cancer is 1 in 13 (7%) (much less risk for non-smokers) according to CancerResearchUK -which explains risk well" 

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