It’s hard nowadays to see your GP without him or her strapping a blood pressure cuff to your arm, quizzing you about your smoking habits, or testing your cholesterol.
We hijack you in this way because all these measurements help us to calculate your risk of heart disease and stroke (known as cardiovascular disease). If we know your risk, we can then give you specific advice and, if necessary, treatments to lower it.
But there's mounting concern that the way we calculate your risk is flawed. If that’s the case then thousands of people could be taking unnecessary medication, such as statins, to reduce cholesterol, while others might not be getting the treatment they need.
Flaws in the scores
For the past 15 years or so, GPs have been calculating the risk of cardiovascular disease in otherwise healthy people using a scoring system based on smoking, blood pressure, 'good' (HDL) and 'bad' (LDL) cholesterol, and age and sex.
In the early days, we used special charts to read off your risk score. Now we type the numbers into our computer and special software works out your percentage risk of developing heart disease or stroke over the next ten years.
This calculation needs to be as accurate as possible because it’s often the basis for recommending that you start taking medicines for life.
National guidance now recommends statin medication (to lower cholesterol) and blood pressure treatment are considered for everybody with a ten-year risk of cardiovascular disease of greater than 20 per cent.
The problem is the risk score is based on a study of about 5,000 largely white, well-off Americans carried out nearly 40 years ago, when cardiovascular disease was particularly rife in the USA. There's evidence this study (the Framingham Heart Study) may be overestimating the risk in today’s northern European populations by as much as 50 per cent.
Plus there are concerns that the Framingham scoring system underestimates the risk of cardiovascular disease in women and people living in deprived areas.
You may be wondering, given these flaws, why the Framingham scoring system has been embedded in your GP's computer for the past 15 years? The answer is it has been the best scoring system on offer, and its strengths and weaknesses have been well studied.
Two new scores
The good news is there are now two new scores, which may be more appropriate for predicting cardiovascular risk in the UK. One, called ASSIGN, is based on data from about 13,000 people living in Scotland in the 1980s and 90s, and includes a measure of social deprivation.
The other, called QRISK, is based on data from 1.3 million patients in UK general practices gathered over the past 12 years or so.
Like ASSIGN, it takes into account whether you have a family history of heart disease, as well as social deprivation, but it also includes relevant information such as whether you are on blood pressure treatment and your body mass index.
The result is a score that tends to classify fewer people as being at high risk of cardiovascular disease. A recent study suggests QRISK puts 3.2 million adults in the UK under the age of 75 in the high-risk bracket, compared with 4.7 million using Framingham scores and 5.1 million using ASSIGN.
It’s important to say that many people currently said to be at high risk would also be classified as high risk using the new scoring system. But in general, QRISK reduces the overall number of people predicted to be at risk, and more accurately identifies those who really are at high risk.
Recommended by NICE
The National Institute for Health and Clinical Excellence (NICE), which guides doctors on best practice, has recently recommended that the QRISK formula is adopted across medical practices in England and Wales, replacing the current Framingham risk score. (The recommendation is out for public consultation before it can be adopted.)
According to QRISK project leader Julia Hippisley-Cox: "If adopted nationally we estimate QRISK could save many thousands of lives by more accurately identifying those at risk. It will also improve the quality of day-to-day life for many patients."
Adopting QRISK would also have implications for the NHS drug budget: statins are prescribed at a cost of £2bn a year. It's likely that bill would be cut, but more prescriptions would be going to people who really need them, particularly women and those from deprived populations.
What does it mean for you?
My feeling is that if I recommend you take medications for life, I'd better be as sure as I can be that you really need them. I also want to be sure my risk-scoring system picks up people who are really are at risk. And that means using the best possible risk score on which to base my advice.
On the face of it, a system based on recent data from more than a million people in the UK is likely to be more relevant than one based on a few thousand people in the USA 30 years ago. But it’s not that simple.
Leading experts on heart disease and high blood pressure have warned that NICE’s plans to replace the Framingham score with QRISK on practice computer systems would cause massive disruption with no proof of benefit.
Some suggest QRISK is based on a register of patient information that has huge amounts of missing data, and say it's not a substantial improvement on the tried-and-tested Framingham system.
And in case you’re thinking you can throw away your pills, NICE isn't recommending QRISK be used to reassess risk in people who've already been identified as having a high risk of cardiovascular disease and are being treated.
And the same goes for people with existing cardiovascular disease, or a condition that automatically puts them at high risk, such as diabetes or familial hypercholesterolaemia.
Dr Graham Easton works in a London GP practice with around 10,000 patients. It has three GP partners, three salaried doctors and fully computerised medical records. His medical training was at The Royal London Hospital. He's also an experienced medical journalist who has worked for BBC Radio Science and the British Medical Journal.
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Fitness Consultant , Basingstoke