Signature
C_mix = sum_(j=1)^J (w_j * C_j)
| Inputs | Definition | Unit |
|---|---|---|
w_j | Proportion of the comparator population receiving current-care option j | proportion |
C_j | Expected relevant cost of current-care option j | currency per defined population or person |
C_mix | Treatment-share-weighted expected cost of the mixed comparator | currency per defined population or person |
|---|
JNumber of mutually exclusive current-care options represented in the mixed comparator (count)
Function
Mixed-comparator construction function
Maps the treatment shares and expected results of current-care options to a weighted mixed comparator.
Try this function
Implementations
Excel
Calculate weighted comparator cost
Excel multiplies each option cost by its treatment share and adds the products.
=SUMPRODUCT(TreatmentShares,OptionCosts)
Assumptions
Valid treatment shares
Treatment shares are non-negative and sum to 1 across the mutually exclusive comparator options.
Representative current practice
Treatment shares reflect the expected comparator mix for the relevant population, setting and period.
Consistent costing basis for mixed comparator
Option costs use the same perspective, population, time horizon, currency and price year.
Worked examples
Weighted comparator cost
Current care consists of Option A for 70% of patients at £10,000 each and Option B for 30% at £15,000 each. Mixed-comparator cost is £11,500 per patient.
J = 2; w_j = [0.70,0.30]; C_j = [10000,15000]; C_mix = 11500
Common errors
Using outdated treatment shares
A mixed comparator based on historical or irrelevant treatment shares may not represent the decision-maker's expected current practice.
Sources
NICE manual on comparators from established practice
National Institute for Health and Care Excellence. NICE technology appraisal and highly specialised technologies guidance: the manual (PMG36). Published 31 January 2022, last updated 13 October 2026. Sections 2.2.12 to 2.2.13 (The scope: comparators) and 6.2.2 to 6.2.3 (Committee recommendations: comparators).
ISPOR report on costing a treatment mix
Sullivan SD, Mauskopf JA, Augustovski F, Jaime Caro J, Lee KM, Minchin M, et al. Budget impact analysis: principles of good practice. Report of the ISPOR 2012 Budget Impact Analysis Good Practice II Task Force. Value in Health. 2014;17(1):5-14.
Canonical Identity
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