Signature
ICUR = Delta_C / Delta_QALY
| Inputs | Definition | Unit |
|---|---|---|
Delta_C | Difference in total relevant cost between the intervention and comparator | currency per defined population or person |
Delta_QALY | Difference in quality-adjusted life years between the intervention and comparator | QALYs per defined population or person |
ICUR | Additional cost per additional quality-adjusted life year | currency per QALY gained |
|---|
Function
Incremental cost-utility function
Maps incremental cost and incremental quality-adjusted life years to the additional cost per QALY gained.
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Implementations
Excel
Calculate cost per QALY gained
Excel divides incremental cost by incremental QALYs using named ranges and returns #N/A when incremental QALYs equal zero.
=IF(IncrementalQALYs<>0,IncrementalCost/IncrementalQALYs,NA())
Assumptions
Relevant comparator for cost-utility analysis
The comparator represents the healthcare choice actually available to the decision-maker.
Consistent analytical basis for cost-utility analysis
Costs and QALYs for both alternatives use the same population, perspective, time horizon and applicable discounting conventions.
Comparable QALY measurement
QALYs for both alternatives use compatible utility evidence and the same timing convention.
Positive incremental QALYs for threshold comparison
The ICUR reads as additional cost per QALY gained, and is compared with a threshold in the usual direction, only when Delta_QALY is greater than zero. When Delta_QALY is negative the ratio is the saving per QALY forgone and the threshold comparison reverses, and when Delta_QALY equals zero no ratio is calculated.
Dominance assessed
The signs of incremental cost and incremental QALYs are examined before the ratio is interpreted.
Worked examples
Cost per QALY gained
Current care has discounted costs of £20,000 and produces 6.60 discounted QALYs. A new intervention has discounted costs of £28,000 and produces 7.10 discounted QALYs. Incremental cost is £8,000 and incremental QALYs are 0.50, so the ICUR is £16,000 per QALY gained.
Delta_C = 8000; Delta_QALY = 0.50; ICUR = 16000
Common errors
Interpreting a negative ICUR mechanically
A negative ratio may indicate either dominance or being dominated and cannot be interpreted without examining incremental cost and incremental QALYs.
Reading a south-west ratio as cost per QALY gained
When incremental cost and incremental QALYs are both negative, the ICUR is positive but measures the saving per QALY forgone. The intervention is then favoured only if the ratio exceeds the threshold, so a ratio below the threshold counts against it.
Sources
NICE manual for cost-utility analysis
National Institute for Health and Care Excellence. NICE technology appraisal and highly specialised technologies guidance: the manual (PMG36). Published 2022; last updated 13 October 2026. Chapter 4 Economic evaluation, sections 4.2.14 to 4.2.16 (cost-utility analysis, QALYs and the definition of the ICER).
Canonical Identity
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