Which overestimates cardiovascular disease risk more, QRisk3 (Quadratic Risk Score 3) or modified Framingham risk score?

Which Risk Calculator Overestimates More: Modified Framingham vs QRisk3?

Modified Framingham overestimates cardiovascular disease risk more than QRisk3, particularly in modern populations and higher-risk groups. 1

Evidence of Framingham Overestimation

The modified Framingham Risk Score (FRS) has been consistently shown to overestimate cardiovascular risk when applied to contemporary populations:

• In validation studies, the Framingham algorithm over-predicted 10-year cardiovascular disease risk by 35% in UK populations, while QRisk3 over-predicted by only 0.4% 2
• In multiple large-scale primary prevention cohorts (Women's Health Study, Physicians' Health Study, Women's Health Initiative), Framingham demonstrated significant overestimation of risk 1
• The ATP-III version of FRS for hard CHD events was previously shown to overestimate risk 1
• Framingham equations tend to overestimate actual risk in Hispanic-American and Asian-American populations 1

QRisk3 Performance and Calibration

QRisk3 demonstrates superior calibration to modern populations:

• QRisk3 was better calibrated to UK populations than Framingham, with only 0.4% over-prediction versus 35% for Framingham 2
• In the original validation cohort, QRisk3 showed excellent discrimination (C-statistic 0.88 in women, 0.86 in men) and explained 59.6% of variation in women and 54.8% in men 3
• QRisk3 includes additional risk factors (chronic kidney disease, systolic blood pressure variability, migraine, corticosteroids, SLE, severe mental illness) that improve risk stratification without sacrificing calibration 3

Clinical Implications of the Difference

The magnitude of overestimation has substantial treatment implications:

• Using Framingham, 13% of patients aged 35-74 would be classified as high risk (≥20% 10-year risk) compared to only 8.5% using QRisk3 2
• In elderly populations, Framingham classifies 86% of men aged 64-75 as high risk versus 73% with QRisk3, and 24% of women versus 34% with QRisk3 2
• UK population estimates suggest Framingham would identify 4.7 million high-risk patients versus 3.2 million with QRisk3—a difference of 1.5 million patients potentially overtreated 2

Important Caveats About Both Calculators

Both calculators have limitations in specific populations:

• Framingham overestimates in Hispanic-American, Asian-American, and lower-risk white cohorts 1
• QRisk3 has not been extensively validated outside UK populations, though it performs well in diverse ethnic groups within the UK 3
• Both calculators may underestimate risk in younger individuals and certain minority populations 4
• The ACC/AHA Pooled Cohort Equations (not specifically asked about but relevant) also overestimate risk by 35-36% in validation cohorts 1

Practical Recommendation

Use QRisk3 when available, particularly for UK or similar populations, as it provides more accurate risk estimates and reduces potential overtreatment 2. If using modified Framingham, recognize that it will likely overestimate risk by approximately 35% in contemporary populations, particularly in patients with calculated 10-year risk >10% 1, 2.