What is ASSIGN?

ASSIGN (v2.0)

ASSIGN is a cardiovascular risk score, which estimates the 10 year percentage risk of developing cardiovascular disease (coronary heart disease, stroke, and transient ischaemic attack) for individuals in Scotland, who do not currently have a diagnosis of cardiovascular disease. 

The name is derived from "ASsessing cardiovascular risk using SIGN guidelines to assign preventive treatment".

The ASSIGN score was developed in 2006 by Professor Hugh Tunstall-Pedoe and Professor Mark Woodward based at the University of Dundee, Scotland, working with the Scottish Intercollegiate Guidelines Network (SIGN) group on cardiovascular risk estimation.

ASSIGN was the first cardiovascular risk score globally to incorporate social deprivation as a risk factor. Its aim is to prioritise prevention of cardiovascular disease for those who stand to benefit most from advice and treatment to reduce their risk. The ASSIGN score has been used across NHS Scotland since its launch in 2006. 

ASSIGN was developed and launched alongside SIGN guideline 97: Risk estimation and the prevention of cardiovascular disease. This was replaced by SIGN guideline 149: Risk estimation and the prevention of cardiovascular disease3 in 2017. There are plans to review and update SIGN 149 in 2025. 

The original authors supported with the development of this Right Decision Service version of the calculator and ASSIGN was also recalibrated in 2024 with contributions from Professor Paul Welsh, University of Glasgow and Dr Dorien Kimenai, University of Edinburgh. The equation underwent a recentering and updating of baseline hazards, based on contemporary cohort studies, to reflect changing trends in population cardiovascular disease event rates since its initial development in 2006. This process did not change the coefficients for individual cardiovascular disease risk factors.

Rheumatoid arthritis was removed as a variable having been temporarily added in 2014 and the SIMD data values were updated to the SIMD 2020 version.

The result of this update is the ASSIGN (v2.0) cardiovascular risk calculator, which is now registered with the UK Medicines and Healthcare products Regulatory Agency (MHRA) as a Class 1 medical device.

 

ASSIGN (v2.0) score and risk threshold

The ASSIGN (v2.0) score is the estimated risk percentage of developing cardiovascular disease over ten years. A score of 10 means a 10% risk of developing cardiovascular disease over ten years, and is considered to be high risk. 

A high score (≥ 10) does not mean that the individual will definitely have a myocardial infarction (MI) or stroke. It does mean that their chances of having such an event are higher than someone with a score below 10. Similarly, an ASSIGN (v2.0) score under 10 does not mean that the person will never have an MI or stroke.

The key consideration is identifying and prioritising those at high cardiovascular risk who will benefit most from targeted intervention and risk reduction. The score should be applied within the context of the most recent relevant guidelines and recommendations for the person's individual health needs as part of a person-centred approach.

The following groups should be assumed to be at high risk and do NOT require risk assessment
with ASSIGN or other cardiovascular risk scoring systems.

  • Individuals with with CKD (eGFR<60) or micro/macroalbuminuria,
  • Individuals with familial hypercholesterolaemia (FH) 
  • Individuals with diabetes aged >40years.
  • Individuals with diabetes aged <40 years with duration of diabetes ≥20 years or micro/macroalbuminuria, or other end organ damage, or with significant other risk factors in the view of the healthcare professional. 

The threshold of 10% is a response to the recalibration of the calculator and is an update to the SIGN 149 recommendation that asymptomatic individuals should be considered at high risk if they are assessed as having a ≥20% risk of a first cardiovascular event within ten years.

Full details on this change are available in FAQs: Why Is the ASSIGN threshold for high risk different from that in SIGN guideline 149?

 

Social deprivation and cardiovascular risk

ASSIGN was the first cardiovascular risk score globally to incorporate social deprivation as a risk factor.

The study published in Heart in 20062 showed a large gradient in coronary heart disease risk in Scottish men and women related to their socioeconomic status, defined by the Scottish Index of Multiple Deprivation (SIMD) but inadequately explained by conventional risk factors. Professors Tunstall-Pedoe and Woodward extended the study to cardiovascular disease as the endpoint, rather than just coronary heart disease.

See Scottish Index of Multiple Deprivation (SIMD) for further information on SIMD.

Study populations

The original ASSIGN score was based on data from 13,000 Scottish men and women recruited between 1984-1995, who had their risk factors measured and were followed up until 2006 (Scottish Heart Health Extended Cohort -more information in 1997 cohort study1 )

The ASSIGN (v2.0) recalibration process used data from a combined total of 44,947 individuals recruited to the Scottish population sub-study of UK Biobank and the Generation Scotland Scottish Family Study Health Cohort between 2006-2010.

ASSIGN equations

Risk score equations

Variable Definitions:
sex: Biological sex (1 = male, 0 = female)
age: Age at recruitment (years, continuous)
chol: Total cholesterol (mmol/L, continuous)
hdl: HDL cholesterol (mmol/L, continuous)
sbp: Systolic blood pressure (mmHg, continuous)
dm: Diabetes mellitus (binary: 1 = yes, 0 = no)
fhxcvd: Family history of CVD in mother, father, or sibling (binary: 1 = yes, 0 = no)
ncig: Number of cigarettes smoked per day (continuous)
simdscore10: Scottish Index of Multiple Deprivation (SIMD) score divided by 10 (continuous).

1. Original ASSIGN (ASSIGN version 1.0)
asm = 0.05698*Age + 0.22286*chol - 0.53684*hdl + 0.01183*sbp + 0.81558*dm + 0.275*fhxcvd +
0.02005*ncig + 0.06296*simdscore10 if sex==1
asf = 0.07203*Age + 0.12720*chol - 0.55836*hdl + 0.01064*sbp + 0.97727*dm + 0.492*fhxcvd +
0.02724*ncig + 0.09386*simdscore10 if sex==0
lbarm = 0.05698*48.8706 + 0.2286*6.2252 - 0.53684*1.35042 + 0.01183*133.810 +
0.81558*0.0152905 + 0.275*0.263762 + 0.02005*7.95841 + 0.06296*2.74038 if sex==1
lbarf = 0.07203*48.7959 + 0.1272*6.40706 - 0.55836*1.62837 + 0.01064*130.115 +
0.97727*0.0127275 + 0.492*0.326328 + 0.02724*6.44058 + 0.09386*2.82470 if sex==0
maleA = (asm-lbarm)
femA = (asf-lbarf)
maleB = exp(maleA)
femB = exp(femA)
Original ASSIGN (males) = 100*(1-(0.8831^maleB))
Original ASSIGN (females) = 100*(1-(0.9365^femB))


2. Recalibrated ASSIGN (ASSIGN version 2.0)
Original ASSIGN score beta coefficients - equation recentred using observations from derivation
cohort, as well as updated baseline hazards from the derivation cohort
gen lbarm2 = 0.05698*55.3999 + 0.2286*5.5488 - 0.53684*1.2944 + 0.01183*141.5754 +
0.81558*0.0481 + 0.275*0.5620 + 0.02005*2.0560 + 0.06296*1.4701 if sex==1
gen lbarf2 = 0.07203*55.1321 + 0.1272*5.8199 - 0.55836*1.6086 + 0.01064*135.2402 +
0.97727*0.0268 + 0.492*0.6129 + 0.02724*1.6107 + 0.09386*1.4740 if sex==0
maleA2 = (asm-lbarm2)
femA2 = (asf-lbarf2)
maleB2 = exp(maleA2)
femB2 = exp(femA2)
Recalibrated ASSIGN (ASSIGN2) (males) = 100*(1-(0.9130^maleB2))
Recalibrated ASSIGN (ASSIGN2) (females) = 100*(1-(0.9666^femB2))