Concept Architecture
Concept
Theoretically, Cost-Effectiveness is the extent to which a healthcare intervention achieves desired health outcomes relative to the resources required to produce those outcomes. The concept is founded on welfare economics and economic efficiency, recognising that healthcare resources are limited and should be allocated to maximise health gain. Cost-effectiveness provides the theoretical basis for comparing alternative interventions by considering both their costs and their consequences, thereby supporting rational healthcare resource allocation.
Mathematically, cost-effectiveness is represented as the relationship between costs and health outcomes. Although the concept itself is general, it is most commonly quantified using the Incremental Cost-Effectiveness Ratio (ICER), which compares the additional cost of one intervention with the additional health benefit achieved relative to an alternative. Other mathematical measures, such as Net Monetary Benefit (NMB) and Incremental Net Benefit (INB), are also used to express cost-effectiveness within decision-analytic frameworks.
In practice, cost-effectiveness is assessed using decision-analytic models, randomised controlled trials, observational studies or combinations of clinical and economic evidence. Costs are measured in monetary units, while outcomes are commonly expressed as quality-adjusted life-years (QALYs), life-years gained or disease-specific clinical outcomes. Cost-effectiveness evidence forms a central component of health technology assessment and is widely used by reimbursement agencies to inform funding and pricing decisions.
Purpose
Used to evaluate whether a healthcare intervention provides sufficient health benefit relative to its cost, thereby supporting healthcare resource allocation, reimbursement decisions and health technology assessment.
Mathematical Formulae
Primary Formula
Incremental Cost-Effectiveness Ratio (ICER):
ICER = (C? ? C?) / (E? ? E?)
where:
- C? = cost of the intervention
- C? = cost of the comparator
- E? = effectiveness of the intervention
- E? = effectiveness of the comparator
Supporting Formulae
Incremental Cost:
?C = C? ? C?
Incremental Effect:
?E = E? ? E?
Net Monetary Benefit:
NMB = ?E ? C
Incremental Net Benefit:
INB = ??E ? ?C
where:
- ? = willingness-to-pay threshold
Related Mathematical Methods
- Cost-Effectiveness Analysis
- Incremental Cost-Effectiveness Ratio
- Net Monetary Benefit
- Incremental Net Benefit
- Cost-Utility Analysis
- Decision-Analytic Modelling
Example
A new oncology treatment costs �42,000 per patient and produces 4.8 QALYs. Standard care costs �30,000 and produces 4.2 QALYs.
Incremental Cost:
?C = �42,000 ? �30,000 = �12,000
Incremental Effect:
?E = 4.8 ? 4.2 = 0.6 QALYs
ICER = �12,000 � 0.6 = �20,000 per QALY gained
If the decision threshold is �30,000 per QALY, the intervention would generally be considered cost-effective.
Excel Implementation
| Function | Example Formula | Health Economics Application |
|---|---|---|
| IFERROR | =IFERROR((B2-C2)/(D2-E2),"Undefined") | Calculates the ICER while handling zero incremental effects. |
| LET | =LET(DC,B2-C2,DE,D2-E2,DC/DE) | Improves readability of ICER calculations. |
| SUM | =SUM(CostRange) | Aggregates costs used in economic evaluation. |
| SUMPRODUCT | =SUMPRODUCT(CostRange,ProbabilityRange) | Calculates expected costs in decision models. |
| IF | =IF(ICER<Threshold,"Cost-Effective","Not Cost-Effective") | Compares the ICER with a willingness-to-pay threshold. |
VBA (Optional)
VBA can automate cost-effectiveness analyses across multiple interventions, generating ICERs, net benefit estimates and sensitivity analyses for health technology assessment.
Sources
- Drummond MF, Sculpher MJ, Claxton K, Stoddart GL, Torrance GW. Methods for the Economic Evaluation of Health Care Programmes. Oxford University Press.
- Briggs A, Claxton K, Sculpher M. Decision Modelling for Health Economic Evaluation. Oxford University Press.
- Gold MR, Siegel JE, Russell LB, Weinstein MC. Cost-Effectiveness in Health and Medicine. Oxford University Press.
- NICE. Health Technology Evaluation Manual.
- ISPOR Good Research Practices for Cost-Effectiveness Analysis.
Related Concepts (2)
Library
Publications
1
Methods for the Economic Evaluation of Health Care Programmes — Drummond, Sculpher, Claxton, Stoddart & Torrance, 4th Edition ed., 2015 (Oxford University Press)
The standard international reference text for economic evaluation methods in health care, covering cost-effectiveness, cost-utility and cost-benefit analysis, measurement of costs and outcomes, evidence synthesis, and the characterisation of uncertainty.
BookView source →
Economic evaluation — National Institute for Health and Care Excellence, Technology appraisal and highly specialised technologies guidance manual ed., 2026 (NICE)
Official methods guidance for comparative economic evaluation, including incremental analysis, ICERs, comparators and the treatment of dominated options.
Web GuidanceView source →
Frequently Asked Questions (6)
What is cost-effectiveness?
A property describing the relationship between an intervention's cost and its health effect relative to an alternative, usually summarised as an incremental cost-effectiveness ratio.
Source: Drummond MF, Sculpher MJ, Claxton K, Stoddart GL, Torrance GW. Methods for the Economic Evaluation of Health Care Programmes. 4th ed. Oxford University Press; 2015.
Is cost-effectiveness a property of an intervention?
Not on its own. It describes a relation between two options, so an intervention is cost-effective relative to a stated comparator, at a stated threshold, in a stated population, and changing any of these changes the answer. The same treatment can be cost-effective against usual care and not against a newer alternative. Describing something as cost-effective without naming what it was compared against is therefore incomplete, and it is the commonest way the term is misused.
Source: Drummond et al. 2015
Does cost-effective mean the same as cost-saving?
No, and conflating them is a persistent error. A cost-saving intervention costs less than its comparator and produces at least as much health, which makes the decision straightforward. A cost-effective intervention usually costs more and produces enough additional health to be worth the additional cost at the threshold applied. Most interventions found to be cost-effective increase spending. A claim that adopting an intervention will save money is therefore a stronger claim than a claim that it is cost-effective, and requires different evidence.
Source: Drummond et al. 2015
What is dominance in cost-effectiveness?
An option is dominated when another costs less and produces more health, in which case it can be discarded without reference to any threshold, since no willingness to pay would justify it. Extended dominance applies where an option is beaten by a combination of two others, and it too can be removed before the remaining options are compared. Identifying and removing dominated options is the first step in any comparison of more than two alternatives, and doing it correctly changes which incremental ratios are meaningful.
Source: Drummond et al. 2015
How is cost-effectiveness summarised?
Usually as an incremental ratio, dividing the difference in cost between two options by the difference in health effect, which states what the additional health costs. An alternative is net benefit, which converts the health gain into money at the threshold and subtracts the cost, giving a figure that is positive where the option is worthwhile. Net benefit behaves better statistically, since ratios become unstable when the difference in effect is close to zero, and it is preferred where uncertainty is being characterised.
Source: Weinstein & Stason 1977
What does cost-effectiveness not tell a decision maker?
It says nothing about affordability, since an intervention can be cost-effective and cost more in total than the budget can accommodate. It says nothing about who gains and who loses, since a quality-adjusted life year counts equally whoever receives it. It does not address severity of the condition treated, or whether the recipients are already disadvantaged. Frameworks applying it therefore attach further considerations rather than deciding on the ratio alone.
Source: Neumann, Sanders et al. 2016
Trust Record
Verified by Dr Darrin Baines
British health economist
Professional identity: darrinbaines.org
Verification date: 5 Aug 2025
Content version: 1.0.0
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- https://healtheconomics.wiki/concept/cost-effectiveness
- Term code
- HE-EE-CEA-008
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