Vascular screening will misclassify risk in hundreds of thousands

24 Feb 09

PCTs are gearing up to roll out screening for everyone aged 40 to 74 from April, but two teams of researchers have concluded the move will mean affluent men are overtreated with statins but women and less affluent patients will miss out.

The Scottish ASSIGN tool would be far more effective than the Framingham score used in the screening programme at identifying risk in women and socially disadvantaged patients, the researchers are claiming.

A University of Dundee study submitted to the BMJ concludes ASSIGN, which is routinely used in Scotland, is significantly fairer than Framingham. It reports that in socially deprived groups, ASSIGN identifies 30% of men and 25% of women, compared with 34% of men and 19% of women using Framingham.

Study leader Professor Hugh Tunstall-Pedoe, one of the developers of ASSIGN and head of the cardiovascular epidemiology unit at the University of Dundee, said ASSIGN should be used south of the border too.

‘ASSIGN abolishes the social gradient in undertreatment of cardiovascular disease, whereas Framingham will be treating a lot of wealthy people who will not go on to develop CVD,’ he said.

Meanwhile, the independent evaluation for NICE of Framingham, ASSIGN and the QRISK score – obtained by Pulse under the Freedom of Information Act – also backs ASSIGN.

The University of East Anglia study showed ASSIGN had better discrimination than Framingham and QRISK and should be considered as an ‘alternative model’ for CVD risk assessment.

Dr Beatriz de la Iglesia, one of the authors and a lecturer in computing sciences at the University of East Anglia, said ASSIGN had a better gradient of deprivation and was better at predicting family history.

‘It is a shame ASSIGN was not considered. It performs better than QRISK and Framingham. It is from a cohort database and has no missing values, whereas QRISK is from a primary care database with missing values.’

Dr de la Iglesia is preparing a paper for publication comparing the scores.

Professor Neil Poulter, professor of preventive cardiovascular medicine at Imperial College London and a board member of the British Hypertension Society, said ASSIGN was a good score, but questioned whether it was worth changing: ‘Overall, Framingham ranks people pretty well, but the absolute level of risk isn’t necessarily spot on.’