Net Health Benefit

Net Health Benefit and the Health Displaced at the Threshold

Net health benefit (NHB) reports a cost-effectiveness result in QALYs instead of money or a ratio. In its incremental form, incremental net health benefit (INHB), it is the extra health a new option produces minus the health that its extra cost would have produced had the money stayed with other care, so a positive value means population health rises on adoption and a negative value means it falls. The NICE manual for technology appraisal (PMG36) asks for expected net health benefits to be presented alongside ICERs, and a 2026 report on uncertainty from the Health Economics Methods Advisory (HEMA) recommends reporting expected INHB alongside the ICER at individual and population levels.

The net benefit approach page gives the history, net benefit the whole family, and net monetary benefit and incremental net monetary benefit the money form.

The formula for health gained less health displaced

Net health benefit can be calculated for each option or for the difference between two options. Decisions turn on the difference, so the incremental form, INHB, is the one most often reported.

$$\text{NHB}_j = E_j - \frac{C_j}{\lambda}, \qquad \text{INHB} = \Delta E - \frac{\Delta C}{\lambda}$$

where $E_j$ and $C_j$ are the expected QALYs and expected cost of option $j$, $\Delta E$ and $\Delta C$ are the differences in QALYs and cost between the new option and its comparator, and $\lambda$ is the cost-effectiveness threshold in money per QALY. INHB equals the NHB of the new option minus the NHB of the comparator.

Stinnett and Mullahy, who set out the measure in 1998, read the subtracted term as the health that could have been gained by investing the same resources in a marginally cost-effective programme. On that reading, a positive INHB means the new option is cost-effective, and a negative INHB means more health could be gained by forgoing it and investing the money elsewhere. They also pointed out that an ICER cannot be read without knowing its quadrant of the cost-effectiveness plane, whereas a positive NHB is always favourable and a negative one always unfavourable, and because NHB is linear in costs and effects its statistical treatment is simpler.

Why the subtracted term is health opportunity cost

The reading of $\Delta C/\lambda$ as health lost elsewhere comes from the budget. Claxton and colleagues, in their 2015 monograph for the NIHR, argued that because NICE has no influence on the size of the NHS budget, its decisions must treat that budget as fixed, so the resources for a more costly technology are found by disinvesting from other services, and that displacement causes health losses for other patients. The threshold then represents the additional cost that has to be imposed on the NHS to forgo one QALY through displacement, and they wrote that cost-effectiveness analysis effectively becomes an analysis of net health benefits. A paper by WHO staff in the Bulletin of the World Health Organization, by Bertram and colleagues, calls thresholds of this kind supply-side, meaning estimates of the health forgone when a payer funds a new intervention and must cut older ones. The opportunity cost page sets out the general idea, and Claxton and colleagues note that the threshold can formally be seen as the shadow price of the budget constraint.

Their illustration uses a technology that adds 2 QALYs per patient. At GBP 20,000 extra cost per patient and a threshold of GBP 20,000 per QALY, 1 QALY is displaced and the net health gain is 1 QALY. At GBP 40,000 the net gain is zero, and at a higher price that displaces 3 QALYs the result is a net loss of 1 QALY. The price at which INHB is zero is the highest price at which adoption does not reduce population health, a price the HEMA report notes is sometimes called the value-based price.

The monograph also contrasts this with a threshold based on the consumption value of health, the rate at which people would give up other consumption for health, sometimes called willingness to pay. Multiplying both health gained and health forgone by the same consumption value cannot change the sign of NHB, so the authors concluded that the size of the threshold for allocating a fixed budget is an empirical question, not a value judgement. Stinnett and Mullahy had allowed both readings, describing $\Delta C/\lambda$ under the second as the minimum health gain society would demand in return for the extra spending.

The empirical estimate for the NHS

Claxton and colleagues estimated how changes in NHS spending affected mortality and quality of life across programme budget categories. Their central estimate was GBP 12,936 per QALY, based on 2008 expenditure and 2008 to 2010 mortality, with probabilities of 0.89 that the threshold was below GBP 20,000 and 0.97 that it was below GBP 30,000. They judged the central estimate more likely to be too high than too low, and argued that the threshold should be lower for technologies with a larger impact on NHS costs, because health effects were greater where local budgets were under more pressure.

Approving ranibizumab for diabetic macular oedema before its patient access scheme, at up to GBP 80 million a year, would have been likely to displace 6,184 QALYs elsewhere in the NHS, which is GBP 80,000,000 divided by GBP 12,936 per QALY.

How NICE uses net health benefit

The NICE manual (PMG36), last updated in March 2026 to include a change to the cost-effectiveness threshold, gives net health benefit a defined place. Section 4.2.16 asks for expected net health benefits as well as ICERs, using values placed on a QALY gain of GBP 25,000 and GBP 35,000, and notes that net monetary benefits can also be shown. It names four cases in which NHB may be particularly informative, namely when decision-making modifiers are applied, when there are several technologies or comparators, when differences in costs or QALYs are small, and when a technology provides less health benefit at lower cost. Section 4.10.8 asks for results in a fully incremental analysis with dominated and extendedly dominated technologies removed, places expected net health benefits alongside it, and adds subgroup considerations to that list.

Section 6.3.1 states that, given the fixed NHS budget, the appropriate maximum acceptable ICER is the opportunity cost of programmes displaced by new, more costly technologies, which is the same basis Claxton and colleagues describe. Section 6.3.2 asks for net health benefits with and without the QALY weighting whenever modifiers are applied. A positive value means overall population health increases; a negative value means the health benefits are not large enough to prevent an overall health loss from care not funded elsewhere. A technology with negative unweighted net health benefit may still be recommended when a modifier applies. The severity modifier in section 6.2.18 weights QALYs by 1.2 or 1.7, using whichever of absolute shortfall or proportional shortfall implies the greater severity.

Expected net health benefit and the cost of uncertainty

Probabilistic sensitivity analysis turns INHB into a distribution, and the HEMA report reads the share of that distribution below zero as the probability that a decision to fund is wrong, which it calls decision uncertainty. The same health scale measures what that uncertainty costs. In the report's simplified example with five possibilities consistent with the evidence, the better treatment has an expected net health benefit of 13 under current evidence, while picking the best treatment in every possibility would give 13.6, so the cost of uncertainty is 0.6 units of health, which is also the EVPI.

The report recommends scaling expected INHB to the population of current patients and setting it beside the population EVPI. Where the health at stake from uncertainty is high compared with the health gained from immediate access, it suggests decision makers may need to consider linking funding to further research. A lower price raises the expected INHB of immediate access and may reduce the cost of uncertainty, although the report notes that it generates no evidence and resolves no uncertainty about treatment effects. Its stated position is that economic evaluation should stay focused on expected population net health benefit, without adjusting for the risk attitudes of decision makers or patients, while the consequences for different groups are made explicit.

Worked example of one technology at three thresholds with a severity weight

All figures in this example are illustrative. A new treatment adds 0.50 QALYs per patient at an extra cost of GBP 14,000 against standard care, an ICER of GBP 28,000 per QALY, and 1,000 patients a year would receive it.

Step 1 calculates INHB at GBP 25,000 per QALY.

$$\text{INHB} = 0.50 - \frac{14{,}000}{25{,}000} = 0.50 - 0.56 = -0.06$$

where 0.50 is $\Delta E$ in QALYs, 14,000 is $\Delta C$ in pounds and 25,000 is $\lambda$. The result is negative, so funding the treatment for 1,000 patients would, at that threshold, mean a net loss of 60 QALYs. At GBP 35,000 the displaced health falls to 14,000 / 35,000 = 0.40 QALYs and INHB becomes 0.10, a net gain of 100 QALYs. The sign changes because the ICER of GBP 28,000 lies between the two values.

Step 2 shows that the money form agrees. Incremental net monetary benefit at GBP 25,000 is 25,000 × 0.50 − 14,000 = −GBP 1,500, which equals 25,000 × −0.06.

Step 3 uses the supply-side estimate. Using Claxton and colleagues' GBP 12,936 per QALY, a 2008 figure applied here only to show scale, the same GBP 14,000 would displace 1.0823 QALYs and INHB would be −0.5823 per patient, a net loss of about 582 QALYs a year.

Step 4 adds a severity weight. If the condition qualifies for the 1.2 QALY weight, applying it to the QALYs gained gives 1.2 × 0.50 − 0.56 = 0.04 at GBP 25,000 and 0.60 − 0.40 = 0.20 at GBP 35,000. The committee would see an unweighted loss of 60 QALYs per 1,000 patients next to a weighted gain of 40. Claxton and colleagues argued that any social weight applied to health gained should also be attached to the health forgone; if the displaced health carried the same weight, the result would be 1.2 × −0.06 = −0.072, still negative.

Step 5 tests a cheaper, less effective option. A de-escalated regimen that loses 0.05 QALYs and saves GBP 2,000 per patient has an INHB of 0.03 QALYs at GBP 25,000, because the money released buys 2,000 / 25,000 = 0.08 QALYs elsewhere, more than the 0.05 QALYs its own patients lose. The same sign rule applies in every quadrant of the cost-effectiveness plane, and this south-west quadrant case is one that PMG36 names.

Net health benefit or net monetary benefit

Because net monetary benefit equals $\lambda$ times net health benefit, the two forms always give the same sign and the same ranking at a positive threshold. Stinnett and Mullahy called the difference in framing mathematically irrelevant, while noting that results in units of health may appeal to those who think debate about health care resources should centre on health, not money.

• Net health benefit suits a decision maker whose threshold represents health displaced, since the result is the change in population health. It also suits analyses with QALY weights, where weighted and unweighted results sit on the same QALY scale, and appraisals for NICE, which asks for it.
• Net monetary benefit suits comparisons with amounts of money, such as a price or the cost of further research in value of information analysis, although the HEMA report states the value of research in health terms too. It is also defined at $\lambda = 0$, where $\Delta C/\lambda$ is undefined, so a net benefit curve drawn from a threshold of zero needs the money form at that point.

Limits and common misreadings

Net health benefit inherits every assumption behind its threshold. Reading INHB at GBP 25,000 or GBP 35,000 per QALY as the literal health lost elsewhere assumes that NHS care is displaced at that cost per QALY, while the monograph's central estimate was about half of GBP 25,000. Claxton and colleagues also listed simplifying assumptions of threshold rules, including constant returns to scale and perfect divisibility of programmes. Affordability is a separate question for budget impact analysis.

• Reporting an NHB without its threshold. Stinnett and Mullahy recommended reporting NHB as a function of $\lambda$ and labelling each estimate with the value used.
• Choosing the option most likely to have the highest NHB instead of the one with the highest expected net benefit. In a HEMA example a medicine with the highest net benefit in only 30% of simulations still had an expected INHB of 0.10 QALYs per patient, because the distribution was right-skewed.

Sources

• Stinnett AA, Mullahy J. Net health benefits: a new framework for the analysis of uncertainty in cost-effectiveness analysis. Medical Decision Making. 1998;18(2 Suppl):S68-S80. doi:10.1177/0272989X98018002S09. Also issued as NBER Technical Working Paper 227, 1998.
• Claxton K, Martin S, Soares M, Rice N, Spackman E, Hinde S, Devlin N, Smith PC, Sculpher M. Methods for the estimation of the National Institute for Health and Care Excellence cost-effectiveness threshold. Health Technology Assessment. 2015;19(14):1-504. doi:10.3310/hta19140
• Bertram MY, Lauer JA, De Joncheere K, Edejer T, Hutubessy R, Kieny MP, Hill SR. Cost-effectiveness thresholds: pros and cons. Bulletin of the World Health Organization. 2016;94(12):925-930. doi:10.2471/BLT.15.164418
• Steuten L, Thavorn K, Cipriano LE, Guertin JR, McQueen B, Schmidler G, Sullivan S, Wailoo A, Sculpher M. Methods to Analyze and Present Uncertainty in Economic Evaluation to Support HTA Decisions. HEMA Report 2. Health Economics Methods Advisory; 2026. Pages ES6, ES10, 2, 8 to 12, 52, 62 and 64.
• 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 4.2.16, 4.10.8, 6.2.18, 6.3.1 and 6.3.2.