QRISK2 outperforms modified Framingham risk score in UK population

26 June 2008

Medwire News: A second version of the QRISK cardiovascular disease (CVD) risk algorithm (QRISK2) is better able to identify high-risk patients than a modified version of the Framingham score, a prospective study in a UK population indicates.

The first QRISK (QRISK1) incorporated indicators of social deprivation, family history, and antihypertensive treatment, as well as traditional risk factors. As reported previously by MedWire News, QRISK1 proved more accurate at predicting CVD risk than the original Framingham score in a study including UK general practice (GP) patients independent of the original derivation and validation cohort.

Julia Hippisley-Cox (University of Nottingham, UK) and colleagues built on QRISK1 to develop a revised algorithm that also incorporates ethnicity, as well as a range of conditions including diabetes, rheumatoid arthritis, renal disease, and atrial fibrillation. They note that a recent recommendation by the UK National Institute for Clinical Excellence to use a modified Framingham risk score, in which a correction factor is applied to determine CVD risk in UK South Asian men, has several limitations.

The researchers developed and validated QRISK2, and compared its performance with the modified Framingham score, using data for over 2 million GP patients at 531 UK practices included in the QRESEARCH database.

The population comprised 2.2 million individuals of White or unrecorded ethnic group and 22,013 South Asian, 11,585 Black African, 10,402 Black Caribbean, and 19,792 Chinese or other Asian or other ethnic groups.

The team reports in the British Medical Journal that QRISK2 showed improved discrimination and calibration compared with the modified Framingham score. QRISK2 explained 43% of the variation in risk in women and 38% of that in men, compared with 39% and 35%, respectively, explained by the modified Framingham score.

Of 112,156 patients classified as high risk, defined as having a 20% or higher risk for CVD over 10 years, by the modified Framingham score, 41.1% would be reclassified as being at low risk using QRISK2, with a 10-year risk of 16.6%.

Conversely, 15.3% of 78,024 patients classified as high risk by QRISK2 (10-year risk of 23.3%) would be reclassified as low risk by the modified Framingham score.

In addition, annual incidence rates for CVD events among those at high risk for QRISK2 were 30.6 and 32.5 per 1000 person-years for women and men, respectively. This is higher than the corresponding rates for individuals at high risk according to the modified Framingham score, at 25.7 and 26.4 per 1000 person-years.

"In other words, at the 20% threshold, the population identified by QRISK2 was at higher risk of a CV event than the population identified by the Framingham score," the authors write.

Hippisley-Cox commented: "Based on the study of 15 years of data from over 2 million UK patients, QRISK2 is a contemporary and specific risk score that allows CVD risk to be personalised to the individual patient."

She added: "QRISK2 has been developed for GPs by GPs, and without the co-operation of thousands of working GPs who freely contribute their data to QRESEARCH, projects like QRISK2 could not happen."

Br Med J 2008; Advance online publication