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Community ASCVD Screening Yield Calculator (NNS & NNT)

  • Average 10-year ASCVD risk among screen-positive individuals (%)
  • Expected LDL-C reduction with chosen therapy (mmol/L)
    Rule of thumb: low-intensity ≈ 0.8; moderate ≈ 1.0; high-intensity ≈ 1.8 mmol/L.
  • Treatment uptake among screen-positive (%)
  • Adherence/persistence at effective dose (%)
  • Screen-positivity (proportion recommended for statin after screening) (%)
    Example: % with PREVENT or PCE risk ≥7.5% or LDL-C ≥190 mg/dL in the screened community.
  • Screening coverage of invited population (%)
  • 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.

    References:
    • CTT Collaboration. Lancet 2010; 376:1670–1681; 2012; 380:581–590.
    • Silverman MG et al. JAMA 2016; 316:1289–1297.
    • Mortensen MB et al. JAMA Cardiol 2019.
    • USPSTF. Statins for Primary Prevention. Evidence Review 2022.

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