Community ASCVD Screening Yield Calculator (NNS & NNT)

Community ASCVD Screening Yield Calculator: Explanation and Clinical Context This tool estimates the yield and population-level impact of community cardiovascular risk screening followed by statin therapy for primary prevention. Inputs include: average 10-year ASCVD risk among screen-positive individuals, expected LDL-C reduction (mmol/L) with the chosen regimen, treatment uptake, adherence, screen-positivity, and screening coverage. The model converts LDL-C lowering into a proportional relative risk reduction (RRR) using the Cholesterol Treatment Trialists’ (CTT) framework: each 1 mmol/L LDL-C reduction ≈ 22% reduction in major vascular events, operationalized as RRR = 1 − 0.78LDLdrop.

The absolute risk reduction (ARR) for an individual = baseline 10-year risk × RRR. NNT = 1 / ARR (over 10 years). The community-level NNS is scaled by screening positivity × effective treatment fraction (uptake × adherence) and coverage.

Outputs include per-screened and per-invited NNS, as well as events prevented per 1000 screened.