Carer

Carer in Economic Evaluation and Health Technology Assessment

In health economics a carer matters for three separate reasons. The carer supplies unpaid time that has an opportunity cost even though no money changes hands, the carer's own health and wellbeing can rise or fall with the patient's condition and treatment, and the carer is often the person who reports outcomes for a patient who cannot report them. The 2021 Census estimated that 5.0 million usual residents of England and Wales aged 5 and over provided unpaid care, so leaving carers out can omit much of what a treatment changes. Van den Berg, Brouwer and Koopmanschap observed that informal care was often neglected in economic evaluations, partly because time is hard to value, and warned that ignoring its costs may lead to undesirable shifts between formal and informal care.

Who counts as a carer in law, statistics and studies

Definitions of a carer vary with their purpose, and an analysis should state which one it uses. They agree on care given outside paid employment but differ at the edges.

The Care Act 2014 defines a carer as an adult who provides or intends to provide care for another adult (section 10(3)). Section 10(9) says an adult is not to be regarded as a carer if the care is provided under or by virtue of a contract or as voluntary work, although section 10(10) lets a local authority treat such a person as a carer when the relationship makes that appropriate. The NICE guideline on supporting adult carers (NG150, 2020) covers adults who provide unpaid care for anyone aged 16 or over with health or social care needs.

The Office for National Statistics uses a household survey definition. An unpaid carer may look after, give help or support to anyone with long-term physical or mental ill-health conditions, illness or problems related to old age, inside or outside the carer's household, and activities done as part of paid employment are excluded. Census 2021 also recorded intensity, with an estimated 1.5 million people in England and Wales providing 50 or more hours of unpaid care a week.

Research definitions are narrower or wider again. Grosse and colleagues define informal care as unpaid care provided by family members to individuals with a medical condition or disability, and note that studies differ on whether only help with daily activities counts or also time spent standing by. The SHEER task force on family and caregiver spillovers left the choice of who is included to the analyst, with sensitivity analyses over a wider or narrower set when it is unclear.

A paid care worker is outside every one of these definitions. The worker's time is bought, so in a NICE analysis it appears as a cost to the NHS or personal social services (PSS) when those bodies fund it, while a carer's time has no market price at all.

Three roles a carer plays in an economic evaluation

A single person can enter an evaluation in several places at once. Keeping the roles apart prevents omission and double counting.

The carer as an unpaid input to care

Informal care is a resource, and the carer's hours are its quantity. Koopmanschap and colleagues compare ways of valuing those hours, including the proxy good method (the price of paid help that could replace the care), the opportunity cost method (what the carer gives up) and stated preference methods such as contingent valuation. The measurement and valuation detail sits on the caregiver burden page.

Two assumptions behind these methods concern the carer directly. Grosse and colleagues note that the replacement approach implicitly treats informal and paid care as perfect substitutes, which is unlikely to be the case. They also report evidence that providing informal care may lead to relatively modest reductions in paid work for women and little or no substitution for men.

The carer as a person whose health changes

Caring affects the carer's own health. Van den Berg and colleagues cite increasing evidence that providing informal care may lead to health problems for the caregiver, in terms of both morbidity and mortality. Bobinac and colleagues separate two routes. The caregiving effect is the welfare effect of providing care, and the family effect is the direct influence of a patient's health on others' well-being, the effect of caring about someone rather than caring for them. In a Dutch sample of informal caregivers they found both effects, possibly of comparable size.

The EQ-5D completed by the carer gives a utility on the same scale as the patient's. The CarerQol, introduced by Brouwer and colleagues, combines seven burden dimensions with a visual analogue scale for happiness, and the ASCOT-Carer, validated by Rand and colleagues in unpaid carers in England, measures social care-related quality of life across seven domains. How these scores feed into QALYs is covered on the caregiver quality of life page.

A treatment does not have to change the patient's health to change the carer's. The SHEER report gives the example of an organisational intervention that discharges patients from hospital earlier, which is likely to affect family carers by moving care into the home and increasing informal care, not by changing the patient's health status.

The carer as a respondent and a source of evidence

Carers are also a source of data about the patient. The NICE technology appraisal and highly specialised technologies manual (PMG36) states that health-related quality of life should be measured directly by patients, and that when this is not possible the measurements should come from the person who acts as their carer rather than from healthcare professionals (section 4.3.3).

A proxy report describes the patient's health, so it is kept separate from the carer's own scores. PMG36 also lists the views of carers among the aspects that qualitative evidence submitted to a health technology assessment can usefully assess (section 3.3.18), alongside patients' experience and views.

Where carers sit under each perspective

The perspective of an analysis decides which carer roles are counted. The NICE reference case and a societal perspective differ mainly on the cost side.

PMG36 counts carer health effects in the reference case when they are relevant and evidenced (sections 4.2.7 and 4.3.17). Carer time can be costed only in a separate analysis when the care might otherwise have been provided by the NHS or PSS (section 4.4.24). Grosse and colleagues report that the Second US Panel (2016) called for both to be counted in societal-perspective analyses. The detail of each rule sits on the caregiver burden page.

Worked example of a household with two carers

All figures are illustrative and undiscounted, over one year. A patient with a progressive neurological condition is looked after by a spouse, the primary carer, and an adult daughter who helps at weekends. A new treatment adds GBP 4,000 to NHS and PSS costs and gains the patient 0.10 QALYs. Carer utility decrements, measured with the EQ-5D against age-matched norms, fall from 0.10 to 0.07 for the spouse and from 0.03 to 0.02 for the daughter. Attributable care time falls from 25 to 20 hours a week for the spouse and from 6 to 4 hours a week for the daughter.

1. Carer QALY gains. The spouse gains 0.10 − 0.07 = 0.03 QALYs and the daughter 0.03 − 0.02 = 0.01 QALYs.

2. Cost per QALY with different sets of people counted.

$$\text{ICER} = \frac{\Delta C}{\Delta Q_P + \sum_{j} \Delta Q_j}$$

where $\Delta C$ is the incremental NHS and PSS cost, $\Delta Q_P$ is the patient's QALY gain and $\Delta Q_j$ is the QALY gain of carer $j$ included in the analysis. Counting the patient only, then adding the spouse, then adding both carers gives the following.

$$\frac{4000}{0.10} = 40000 \qquad \frac{4000}{0.10 + 0.03} = 30769 \qquad \frac{4000}{0.10 + 0.03 + 0.01} = 28571$$

where each result is the ICER in GBP per QALY and the denominators are 0.10, 0.13 and 0.14 QALYs.

3. Carer time in a separate analysis. The spouse saves 5 × 52 = 260 hours and the daughter 2 × 52 = 104 hours, 364 hours in total. At an illustrative replacement cost of GBP 20 an hour, 364 × 20 = 7,280, so the time saved is worth GBP 7,280. Against the extra GBP 4,000, the net cost is 4,000 − 7,280 = −3,280, and with a QALY gain the treatment would dominate standard care in this analysis.

The ratio falls by almost a quarter, from GBP 40,000 to GBP 30,769 per QALY, once the primary carer is counted, and the daughter moves it a further GBP 2,198. Under PMG36 the second and third ratios are reference-case figures only if the evidence required by section 4.3.17 exists, while the time analysis in step 3 is shown separately and is relevant only if the care might otherwise have been provided by the NHS or PSS. A sensitivity analysis over who is counted, as SHEER recommends, shows how far the decision depends on that choice.

How a carer differs from nearby ideas

The carer is the person, and most neighbouring terms describe something about that person. Caregiver burden is the strain caring places on the carer, and caregiver quality of life is the carer's overall wellbeing. Informal care cost is the money value of the carer's time, and patient time cost is the parallel idea for the patient's own time. A relative who gives no care can still experience the family effect without being a carer. A healthcare proxy holds legal authority to decide for a patient, which a carer may or may not have, whereas a carer acting as a proxy respondent only reports on the patient's health. A paid care worker provides care under a contract and belongs in formal care costs.

Limitations and common misreadings

Carers are hard to find and count, and several errors recur. Each can bias the result.

• Hidden carers. NG150 notes that many carers do not think of themselves as carers or are not identified by practitioners, and that in one area only an estimated 7% were identified by health and social care organisations. Samples recruited through services miss many.
• Counting one carer. Restricting the analysis to the primary carer leaves out secondary carers, worth GBP 2,198 per QALY in the example above.
• Total instead of attributable time. Grosse and colleagues warn that total reported hours can overstate the burden of a condition unless hours attributable to it are estimated against a comparison group.
• Double counting. Koopmanschap and colleagues caution that contingent valuation and conjoint measurement values for informal care can overlap with health effects of the patient and carer that have been valued separately.
• One-sided spillovers. Al-Janabi and colleagues show that both the spillovers a new technology generates and those lost with the care displaced to fund it need to be counted, or the analysis favours technologies with large carer effects.

Sources

• Al-Janabi H, van Exel J, Brouwer W, Coast J. A framework for including family health spillovers in economic evaluation. Medical Decision Making. 2016;36(2):176-186. doi:10.1177/0272989X15605094
• Bobinac A, van Exel NJ, Rutten FF, Brouwer WB. Caring for and caring about: disentangling the caregiver effect and the family effect. Journal of Health Economics. 2010;29(4):549-556. doi:10.1016/j.jhealeco.2010.05.003
• Brouwer WB, van Exel NJ, van Gorp B, Redekop WK. The CarerQol instrument: a new instrument to measure care-related quality of life of informal caregivers for use in economic evaluations. Quality of Life Research. 2006;15(6):1005-1021. doi:10.1007/s11136-005-5994-6
• Care Act 2014, c. 23, section 10 (Assessment of a carer's needs for support). https://www.legislation.gov.uk/ukpga/2014/23/section/10
• Grosse SD, Pike J, Soelaeman R, Tilford JM. Quantifying family spillover effects in economic evaluations: measurement and valuation of informal care time. PharmacoEconomics. 2019;37(4):461-473. doi:10.1007/s40273-019-00782-9
• Henry E, Al-Janabi H, Brouwer W, et al. Recommendations for emerging good practice and future research in relation to family and caregiver health spillovers in health economic evaluations: a report of the SHEER task force. PharmacoEconomics. 2024;42(3):343-362. doi:10.1007/s40273-023-01321-3
• Koopmanschap MA, van Exel JN, van den Berg B, Brouwer WB. An overview of methods and applications to value informal care in economic evaluations of healthcare. PharmacoEconomics. 2008;26(4):269-280. doi:10.2165/00019053-200826040-00001
• 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. https://www.nice.org.uk/process/pmg36
• National Institute for Health and Care Excellence. Supporting adult carers (NG150). Published 22 January 2020. https://www.nice.org.uk/guidance/ng150
• Office for National Statistics. Unpaid care, England and Wales: Census 2021. Released 19 January 2023. https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/healthandwellbeing/bulletins/unpaidcareenglandandwales/census2021
• Rand SE, Malley JN, Netten AP, Forder JE. Factor structure and construct validity of the Adult Social Care Outcomes Toolkit for Carers (ASCOT-Carer). Quality of Life Research. 2015;24(11):2601-2614. doi:10.1007/s11136-015-1011-x
• van den Berg B, Brouwer WB, Koopmanschap MA. Economic valuation of informal care: an overview of methods and applications. European Journal of Health Economics. 2004;5(1):36-45. doi:10.1007/s10198-003-0189-y