24 November 2010
The Horns of an Aspirin Dilemma
It is remarkable that the biggest controversy in medicine at the moment is about the second oldest drug in the British National Formulary (1897): aspirin. If nothing else, the controversy inspired me to look up the phrase “horns of a dilemma”. It comes from a question which offers two alternatives, both of which are bad. Rather like the question in court, “When did you stop beating your wife?”
I am looking at two articles at the moment: both of them about aspirin.
ON MY RIGHT is an article in the Daily Telegraph for 24th November under the headline, “All over-45-s ‘should take a daily dose of aspirin“. For an article in a popular daily, it is remarkably well balanced. It is a report of a session at the Royal Society of Medicine where a panel head by Prof Peter Rothwell noted a reduction in people who took low-dose aspirin of bowel cancer by a quarter and deaths by a third. This was balanced by the problem of an increase in the risk of gastro-intestinal bleeding.
Here in large parentheses is a fascinating demonstration of the danger of quoting Relative Risk figures. Most of you would be deterred from taking a drug which doubled your risk of gastro-intestinal bleeding wouldn’t you ? After checking the figures, I wouldn’t. Why ? Well – the risk of hæmorrhage is doubled from 1 in 1000 to 2 in 1000. In other words – double a rarity and it is still rare.
There were some doubters who felt that only those at risk should take aspirin but the majority were in favour of a population strategy.
ON MY LEFT is an article in Diabetes Digest by Vinod Patel in which he tries to sort out some sense from a recent meta analysis of papers trying to answer the question of whether aspirin should be used as a primary prevention measure against cardiovascular disease in diabetes. The analysis showed a non-significant reduction in cardiovascular events of 9%. The conclusion was that aspirin should be “considered” in those at high risk, “no clear evidence” in those at medium risk and “reassess risk” in those at low risk. Hardly clearcut then.
IN THE MIDDLE is Practice Nurse Nay and Mrs Yay. Mrs Yay is 48, has diabetes and has just asked Nurse Nay whether she should take 75mg aspirin a day. Nurse Nay echoes the words of Descartes all those years ago and asks herself, “what do I actually know without any doubt ?” In Nurse Nay’s case, she narrowed the field down to low dose aspirin.
SHE KNOWS that low dose aspirin:
1. Prevents further cardiovascular events in people who have already had one (secondary prevention)
2. Lowers the incidence of bowel cancer
3. Increases the risk of gastro-intestinal hæmorrhage
SHE THINKS that low dose aspirin:
1. May reduce the risk of breast cancer
2. May be of use for the primary prevention of cardiovascular disease
Knowing that Mrs Yay’s mother died of colorectal cancer and that, as far as she knows, no-one in the family has suffered a gastro-intestinal bleed from either aspirin or any other non-steroidal anti-inflammatory drug, Nurse Nay warns Mrs Yay of the possible (rare) risk of low dose aspirin and gives a guarded approval to the suggested course of action.
The jury is still out on the horns of a dilemma on the vexed question of whether aspirin should be put in the water – fluorinated or not.
“Adams S, (2010) All over 45-s ‘should take a daily dose of aspirin’, D Telegraph No. 48,360 1-2”
“Patel V, (2010) Aspirin for primary prevention of cardiovascular disease in people with diabetes: Yay or nay, Diabetes Digest Vol 9 No 4 237”