Risk scores & their limits

Before anyone scans your arteries, guidelines run your numbers through a risk calculator. These are genuinely useful for deciding who to look at more closely — and genuinely blunt as a verdict on any one person. The newest US calculator caused a storm by reclassifying millions overnight.

The calculators

What they estimate: Each turns age, sex, blood pressure, lipids, smoking, and diabetes into a 10-year risk percentage. The US Pooled Cohort Equations were standard; the AHA's new PREVENT equations (2023) added kidney and metabolic factors, dropped race, and extended to 30-year risk — and in doing so roughly halved estimated risk for many people, which by one analysis would make ~40 million fewer Americans statin-eligible. The UK uses QRISK3. Rough bands: <5% low, 7.5–20% intermediate (the decision zone), >20% high.
Why they mislead individuals: Age dominates the math. Most men over 65 clear the threshold almost regardless of their lipids, while a 35-year-old with a terrible ApoB and sky-high Lp(a) can score 'low' because they're young — even though their lifetime risk is severe. The scores also ignore Lp(a), the depth of your family history, and whether you already have plaque. A '10% 10-year risk' is a population frequency, not your personal fate. Excellent for triage; poor as a diagnosis.
The fix: refine, then look: Guidelines patch the gap with risk-enhancers — family history, Lp(a), hs-CRP, metabolic syndrome, ApoB, ethnicity — that nudge borderline people up. But the decisive tie-breaker in the intermediate zone is to stop estimating and look directly at the arteries with a calcium score or CT angiogram. Risk factors predict; imaging shows.

A score decides whether to look closer

Treat a risk calculator as a triage tool that decides whether to investigate further — not as evidence of whether you personally have disease. When the number lands in the intermediate zone, the next move is imaging, not a coin flip.

The Cholesterol Guide