Updating the Scottish national cardiovascular risk score: ASSIGN version 2.0.

Background: The Assessing cardiovascular risk using Scottish Intercollegiate Guidelines Network (ASSIGN) risk score, developed in 2006, is used in Scotland for estimating the 10-year risk of first atherosclerotic cardiovascular disease (ASCVD). Rates of ASCVD are decreasing, and an update is required. This study aimed to recalibrate ASSIGN (V.2.0) using contemporary data and to compare recalibration with other potential approaches for updating the risk score.

Methods: Data from Scotland-resident participants from UK Biobank (2006-2010) and the Generation Scotland Scottish Family Health Study (2006-2010), aged 40-69 and without previous ASCVD, were used for the derivation of scores. External evaluation was conducted on UK Biobank participants who were not residents of Scotland. The original ASSIGN predictor variables and weights formed the basis of the new sex-specific risk equation to predict the 10-year risk of ASCVD. Different approaches for updating ASSIGN (recalibration, rederivation and regression adjustment) were tested in the evaluation cohort.

Results: The original ASSIGN score overestimated ASCVD risk in the evaluation cohort, with median predicted 10-year risks of 10.6% for females and 15.1% for males, compared with observed risks of 6% and 11.4%, respectively. The derivation cohort included 44 947 (57% females and a mean age of 55) participants. The recalibrated score, ASSIGN V.2.0, improved model fit in the evaluation cohort, predicting median 10-year risk of 4% for females and 8.9% for males. Similar improvements were achieved using the regression-adjusted model. Rederivation of ASSIGN using new beta coefficients offered only modest improvements in calibration and discrimination beyond simple recalibration. At the current risk threshold of20% 10-year risk, the original ASSIGN equation yielded a positive predictive value (PPV) of 16.3% and a negative predictive value (NPV) of 94.4%. Recalibrated ASSIGN V.2.0 showed similar performance at a 10% threshold, with a PPV of 16.8% and an NPV of 94.6%.

Conclusions: The recalibrated ASSIGN V.2.0 will give a more accurate estimation of contemporary ASCVD risk in Scotland.