Christchurch Outpatients · 1 Filly Place, Yaldhurst ●  Clinic: Thursday afternoons  ●  admin@inspirehealth.co.nz
Clinical tools · Lipids

Lipid-Lowering Switch Calculator

Enter the current regimen and a measured LDL-C. The tool reconstructs the untreated baseline, then projects what a different regimen would give.

Statin, ezetimibe, bempedoic acid and PCSK9-directed therapy (evolocumab, alirocumab or inclisiran) are modelled as combining multiplicatively, since each reports its reduction on top of background therapy. Educational aid for clinicians — not a substitute for a measured pre-treatment profile or clinical judgement.

Current regimen · measured

Use direct or Martin-Hopkins LDL if low or triglycerides high; Friedewald under-reads at low LDL.
Reconstructed untreated baseline LDL-C
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Switch to · projected

Projected LDL-C

—mmol/L
Range — to —
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ApoB projected —
Current reduction
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Proposed reduction
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LDL-C axis · baseline to current to projected

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Untreated baseline (reconstructed) Current, measured Projected on new regimen
Assumptions and efficacy table
Statin10 mg20 mg40 mg80 mg
Statins: mean LDL-C reduction anchored on STELLAR (Jones 2003); micro-doses (†) extrapolated below RCT range. Ezetimibe 10 mg add-on 22%, 5 mg ~19%. Bempedoic acid 18% on a statin, 21% without (CLEAR Harmony/Wisdom/Serenity); with ezetimibe the multiplicative result matches the ~38% fixed-combo figure. Evolocumab ~60% on or off statin (FOURIER, OSLER), with a tighter response band than statins. Alirocumab is modelled with evolocumab as a single mAb class effect. Inclisiran ~50% (ORION), a twice-yearly siRNA. All three act on the PCSK9 pathway and are therefore mutually exclusive in this tool. ApoB modelled at 0.85 of LDL-C reduction; note bempedoic acid lowers apoB proportionally less (~0.66), so apoB reads slightly optimistic when it is included. Rosuvastatin is Special Authority; bempedoic acid and PCSK9i are not Pharmac-funded (self-pay) as of 2026.

Why switching is more reliable than a bare baseline. The measured LDL already encodes this patient's own response to their current drug. Scaling to a new regimen by the ratio of expected reductions carries much of that individual deviation across.

Combined-therapy caution. With a PCSK9 inhibitor in the current regimen the total reduction can exceed 70%, so the reconstructed baseline is divided by a very small number and becomes little more than an order-of-magnitude estimate. The switch projection survives this better than the baseline figure does.

ApoB. Modelled from LDL-C reduction, not measured. Coarsest when bempedoic acid is included or in high-triglyceride, remnant-rich phenotypes. Treat it as directional.

Educational aid for a clinician. Not a substitute for a measured pre-treatment profile or clinical judgement.

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