Experts validate promising alternative to Framingham risk score for UK

Jun 26 2012

By Piriya Mahendra

Researchers have validated an alternative model to the Framingham risk equation for the prediction of 10-year cardiovascular disease (CVD) risk in the UK, they report in the BMJ.

Results from an independent and external validation of the QRISK2-2011 model indicated good performance data when compared with the UK National Institute of Clinical Excellence (NICE) version of the Framingham equation, say Gary Collins and Douglas Altman (University of Oxford, UK).

Moreover, the QRISK2-2011 model, which differs from earlier versions in its definition of smoking as a five-level variable, was better able to identify individuals at high risk for developing CVD than was the NICE Framingham equation.

Indeed, at the traditional threshold of 20% used to designate an individual at high risk for developing CVD, the QRISK2-2011 model identified five more cases per 1000 men compared with the NICE Framingham equation.

And for women, the net benefit of using QRISK2-2011 at a 20% threshold identified two more cases per 1000, compared with not using any model, or using the NICE Framingham equation.

The authors say that the QRISK2-2011 model is well-calibrated, with "reasonable agreement" between observed and predicted outcomes, whereas the NICE Framingham equation consistently over-predicts risk in men by about 5%, and shows poor calibration in women.

Despite increasing evidence to suggest that the Framingham equation is not well suited to the UK and the QRISK model may be more suitably tailored, there is no firm recommendation as yet on which risk score should be used, leaving healthcare professionals free to choose.

However, the authors write: "The performance data presented in this article provide strong evidence for the use of the updated QRISK2-2011 over the NICE Framingham equation.

"The performance of QRISK2-2011 is noticeably more impressive than the NICE version of the Framingham equation in discrimination, calibration, and clinical utility."

They warn that if the use of the Framingham score must continue, recalibration is necessary to reflect the characteristics of the current UK population. "Without recalibration we urge caution in using the Framingham equation to identify high risk patients in the UK."

The prospective cohort study used routinely collected data from 364 general practices in the United Kingdom that contributed to The Health Improvement Network database. Overall, 2 million patients aged 30-84 years, with 93,564 CV events were included.

The main outcome measure of the study was the first diagnosis of CVD (myocardial infarction, angina, coronary heart disease, stroke, and transient ischemic attack) reported in general practice records.

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