Margin for error

A member of Clan Macheath had a blood test last week as part of a routine check-up. Returning to the surgery for the results, she was told she had 'a risk factor of 15%'.

The nurse seemed surprised to be asked for an explanation; "Look, it's here on the chart: your cholesterol gives you a risk of 15%, see?"

"Yes, but a risk of what, exactly?"

Turns out it's a risk of dying of a heart attack in the next ten years. Now it's not the easiest thing to express without giving the lady's age, but generally speaking this looked like not unreasonable odds of survival (her words, not mine); in any case, like most well-educated people, she knows that medical statistics - like boiled eggs - are best taken with a substantial pinch of salt.

But the nurse had not yet finished; under the circumstances, she said, she would recommend a course of statins. Not a good move; the patient is firmly opposed to blanket prescription and has a particular aversion to the idea of statins - and she's not the only one (see my post Statins for all and a death sentence).

The nurse was clearly disappointed; "Then we'll just have to try and manage it through diet". Manage what? The cholesterol reading was well within normal parameters; either the word 'risk' seems to have triggered a knee-jerk response or the 'statins-for-all' movement is alive and thriving in the hands of blinkered zealots.

One thing that interests me here is that our relative was not told whether to fast before the test. This is presumably because a study in 2009 found that 'cholesterol measurements are at least as good - and probably somewhat better - when made without fasting'.

But if that is so, why does the NHS website - reviewed in 2011 - still clearly advise 'Do not eat anything and only drink water for 10-12 hours before having blood cholesterol tests'? Are doctors, in fact, actively seeking raised readings by ignoring this advice?

This suggests at least some difference of opinion - and implies that the cholesterol test is rather more of a blunt instrument that those acting on its results would like us to believe. Given the very real possibility that statin side-effects will mask the symptoms of serious illness, I would question the ethics of prescribing on these terms.

The complexity of the human body means that diagnosis is not a exact science; to reduce it to box-ticking and percentages on a chart is to act under false pretences and with a dangerous complacency.