What is QRisk2 (cardiovascular risk assessment tool)?

What is QRISK2?

QRISK2 is a cardiovascular risk assessment tool that estimates the 10-year absolute risk of developing coronary heart disease (angina or myocardial infarction), stroke, or transient ischemic attack, specifically calibrated to the British population and updated annually. 1

Key Features and Variables

QRISK2 is distinguished from other risk calculators by its inclusion of a broader range of risk factors beyond traditional variables 1:

Traditional risk factors included:

• Age, sex, systolic blood pressure 1
• Total cholesterol and HDL cholesterol ratio 1
• Smoking status 1
• Diabetes status 1
• Hypertension treatment status 1

Additional risk factors unique to QRISK2:

• Ethnicity (including South Asian, Black African, Black Caribbean, Chinese, and other ethnic groups) 1
• Family history of premature coronary heart disease (in first-degree relative under 60 years) 1
• Socioeconomic deprivation (Townsend deprivation score) 1
• Body mass index 1
• Rheumatoid arthritis 1
• Chronic kidney disease 1
• Atrial fibrillation 1

Clinical Application and Guidelines

The 2014 NICE Guidelines support the use of QRISK2 for global cardiovascular risk assessment in all adults younger than 84 years who are free of cardiovascular disease. 1

The tool is used to guide treatment decisions with specific thresholds 1:

• Statin therapy is recommended for primary prevention in individuals with an estimated 10-year absolute CVD risk of ≥10% 1
• Individuals with type 2 diabetes are also candidates for statin therapy regardless of calculated risk 1
• Patients with type 1 diabetes who are older than age 40, with disease duration over 10 years, or with evidence of target organ damage should receive statin therapy 1

Validation in Diverse Populations

QRISK2 was derived and validated in 2.3 million people to accurately estimate cardiovascular risk in different ethnic groups in England and Wales. 1

The algorithm specifically addresses a critical limitation of other risk calculators 1:

• Unlike previous calculators, QRISK2 counts South Asian ethnicity as an additional risk factor, and median scores for South Asians are higher than those of other tools 1
• Traditional risk calculators like the Framingham Risk Score and ACC/AHA pooled cohort equations underestimate risk in South Asians because they were not derived from or validated in this higher-risk group 1
• QRISK2 may still underestimate risk in South Asian women, but provides more reasonable risk estimates than alternative tools 1

Performance Characteristics

QRISK2 demonstrated improved discrimination and calibration compared with the modified Framingham score in validation studies. 2, 3

Key performance metrics 2, 3:

• The algorithm explained 43% of the variation in women and 38% in men, compared with 39% and 35% respectively by the modified Framingham score 2
• At the 20% treatment threshold, QRISK2 identified a population at higher actual risk than the Framingham score 2
• The annual incidence rate of cardiovascular events among those with a QRISK2 score of ≥20% was 30.6 per 1000 person years for women and 32.5 per 1000 person years for men 2

Important Limitations

QRISK2 performs less well in older people (≥65 years) and those with high multimorbidity, particularly when accounting for competing mortality risks. 4

Specific performance issues 4:

• Discrimination was poor in older age groups (C-statistic <0.65 in all subgroups aged 65 years or older) 4
• The tool systematically over-predicted CVD risk in older people and those with high multimorbidity when accounting for competing risks 4
• Non-CVD death rose markedly with age (20.1% of women and 19.6% of men aged 75-84 years had a non-CVD death during follow-up) 4

Comparison with Other Risk Tools

QRISK2 is more accurate in identifying high-risk populations for cardiovascular disease in the United Kingdom than the NICE version of the Framingham equation. 3, 5

The NICE Framingham equation shows significant limitations 5:

• Consistently over-predicts risk in men by about 5% 5
• Shows poor calibration in women 5
• Has no clinical benefit in either men or women at current thresholds 5

Recommended Use in Clinical Practice

The American Heart Association recommends considering the UK QRISK2 calculator for South Asian patients in the United States, although it is based specifically on the South Asian population in the United Kingdom. 1

For optimal clinical application 1:

• Use QRISK2 for patients younger than 84 years without established cardiovascular disease 1
• The tool is updated annually to maintain calibration to contemporary populations 1
• Consider that the 10-year risk threshold of ≥10% for treatment initiation differs from the ACC/AHA guideline threshold of ≥7.5% 1