Signature
dC_T = C_T_new - C_T_comp; ICER_S = ICER_H + dC_T / dE; g_ICER = (ICER_S - ICER_H) / ICER_H
| Inputs | Definition | Unit |
|---|---|---|
C_T_new | Patient time cost per patient of the new option | currency per patient |
C_T_comp | Patient time cost per patient of the comparator | currency per patient |
ICER_H | Incremental cost per QALY with health service costs only, from HE-FM-ICER-001 | currency per QALY |
dE | QALY gain of the new option over the comparator, the same in both ratios | QALYs per patient |
dC_T | Patient time cost of the new option minus that of the comparator | currency per patient |
|---|---|---|
ICER_S | Incremental cost per QALY when the incremental patient time cost is added to the health service costs | currency per QALY |
g_ICER | Rise in the ICER from adding patient time, as a proportion of the health service ICER | proportion |
Function
Patient time cost function from service use, hours per use and an hourly value of time
Maps the number of times a patient uses each type of health service, the hours each use takes in travel, waiting and care, and an hourly value of time to the money value of the patient's time in care over a period, per visit and in total. It is the resource costing sum HE-FM-COST-001 with patient hours as the resource and the hourly value as the unit cost, so the package keeps only the steps particular to patient time, which are hours built up from service counts (HE-FM-PTC-001 and HE-CF-PTC-001), the change in an incremental cost-effectiveness ratio when the time cost is added (HE-FM-PTC-002) and a value of time that depends on employment status (HE-FM-PTC-003). Productivity cost is a different cost category. The absence records HE-FN-ABSN-001, HE-FM-ABSN-002 and HE-FM-ABSN-003 value time lost from paid work as lost output, under the human capital approach or within the friction period, whereas patient time cost values the hours spent in care whether they are taken from paid work, unpaid work or leisure, and an hour taken from paid work is counted under one heading only. A value of time from another price year is moved with HE-FM-COST-002, time costs in later years are discounted with HE-FN-DISC-001, and a national total from a mean time cost per patient follows HE-FM-COI-001. Notation follows the Patient Time Cost article.
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Implementations
Excel
ICER with incremental patient time from named cells
With the two options' time costs in TimeCostNew and TimeCostComparator, the QALY gain in QALYGain and the health service ICER in HealthServiceICER, the three formulas fill TimeCostIncrement, SocietalICER and ICERRiseShare in turn.
=TimeCostNew-TimeCostComparator; =HealthServiceICER+TimeCostIncrement/QALYGain; =(SocietalICER-HealthServiceICER)/HealthServiceICER
Assumptions
QALY gain unchanged when patient time is costed
dE is the same in both ratios, so patient time enters only the cost side. The article assumes that the QALY gain already captures any effect of treatment on health-related quality of life, so only the hours spent in care are costed; Kim and colleagues note an open question over whether lost productivity from illness is already captured in QALYs, and the same care applies to time spent unwell. The ratio reading needs dE above zero, and g_ICER is read only when ICER_H is above zero, since a health service ICER of zero leaves it undefined and a negative one reverses its sign. With dE of zero the ICER is undefined and the comparison uses HE-FM-NMB-002, or the dominance rule HE-FM-DOM-001 with its treatment of ties.
Perspective that counts patient time in the incremental cost
ICER_S belongs to a limited societal perspective, which Kim and colleagues define as adding patient time, patient transport, unpaid carer time and productivity loss to the costs of the health care sector perspective; this formula adds only patient time, and the other items have their own records. The Second Panel on Cost-Effectiveness in Health and Medicine recommends a health care sector and a societal reference case with an impact inventory, which Breslau and colleagues describe as listing patient-time costs. The NICE manual sets the reference-case perspective on costs as the NHS and PSS (PMG36 sections 4.2.7 and 4.2.9), and its chapter on economic evaluation does not mention patients' own time, so on that perspective ICER_S lies outside the NICE reference case, an inference the article also draws.
Worked examples
Infusion against oral treatment with patient time at GBP 15 an hour
The article's hypothetical infusion costs the health service GBP 1,500 more than the oral treatment and gains 0.10 QALYs, an ICER of GBP 15,000 per QALY (HE-FM-ICER-001). Patient time costs of GBP 1,755 and GBP 360 (HE-EX-PTC-001 and HE-EX-PTC-002) give an incremental time cost of GBP 1,395, an ICER of GBP 28,950 per QALY with patient time and a rise of 93%, as in the article.
C_T_new = 1755; C_T_comp = 360; dE = 0.10; ICER_H = 15000; dC_T = 1395; ICER_S = 28950; g_ICER = 0.93
Infusion against oral treatment with patient time at GBP 7 an hour
At GBP 7 an hour the time costs are GBP 819 and GBP 168 (HE-EX-PTC-003 for the infusion), the incremental time cost is GBP 651 and the ICER with patient time is GBP 21,510 per QALY, a rise of GBP 6,510 as in the article, or 43.4% of the health service ICER (computed here).
C_T_new = 819; C_T_comp = 168; dE = 0.10; ICER_H = 15000; dC_T = 651; ICER_S = 21510; g_ICER = 0.434
Equal patient time for both options leaves the ICER unchanged
When both options take the same patient time, here an illustrative GBP 360 each, the incremental time cost is zero and the ICER keeps its health service value, a limiting case that checks an implementation.
C_T_new = 360; C_T_comp = 360; dE = 0.10; ICER_H = 15000; dC_T = 0; ICER_S = 15000; g_ICER = 0
Common errors
Total patient time cost of the new option added to the incremental cost
Adding the new option's whole time cost rather than the difference from the comparator counts the comparator's patient time as if it were extra. In the article's example the ICER becomes GBP 32,550 per QALY in place of GBP 28,950, GBP 3,600 or 12% too high (computed here for illustration).
Patient time ICER reported as the NICE reference-case result
Reporting ICER_S, GBP 28,950 per QALY in the article's example, as the NICE reference-case result mixes perspectives, since PMG36 section 4.2.9 sets the reference-case perspective on costs as the NHS and PSS, which gives GBP 15,000. PMG36 section 4.4.23 allows costs paid by patients and not reimbursed by the NHS and PSS to be presented separately; showing patient time separately in the same way is an inference, since the manual's chapter on economic evaluation does not mention patients' time.
Sources
Limited societal perspective including patient time defined by Kim and colleagues
Kim DD, Silver MC, Kunst N, Cohen JT, Ollendorf DA, Neumann PJ. Perspective and costing in cost-effectiveness analysis, 1974-2018. PharmacoEconomics. 2020;38(10):1135-1145. Methods, Working Definitions subsection, which defines the limited societal perspective as accounting for cost components beyond those of the healthcare sector perspective, including patient time, patient transportation, unpaid caregiver time and productivity loss; the Discussion names the open question whether lost productivity from morbidity is already captured in measuring QALYs.
Second Panel reference cases and impact inventory for patient time
Sanders GD, Neumann PJ, Basu A, Brock DW, Feeny D, Krahn M, et al. Recommendations for conduct, methodological practices, and reporting of cost-effectiveness analyses: Second Panel on Cost-Effectiveness in Health and Medicine. JAMA. 2016;316(10):1093-1103. Abstract, which recommends that all cost-effectiveness analyses report two reference case analyses, one from a health care sector perspective and one from a societal perspective, and an impact inventory, a structured table of consequences inside and outside the formal health care sector.
Impact inventory listing patient-time costs in the informal health care sector
Breslau RM, Cohen JT, Diaz J, Malcolm B, Neumann PJ. A review of HTA guidelines on societal and novel value elements. International Journal of Technology Assessment in Health Care. 2023;39(1):e31. Methods, subsection on identification of societal and novel value elements, which states that the Second Panel recommended an impact inventory that enumerates societal elements in the informal healthcare sector, namely patient-time costs, unpaid caregiver-time costs and transportation costs.
NHS and PSS perspective on costs in the NICE reference case
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 4.2.7 and 4.2.9, which state that the perspective adopted on costs should be that of the NHS and PSS and that productivity costs should not be included, and section 4.4.23, which states that costs paid by patients may be included when the NHS or PSS reimburses them and that costs paid by patients and not reimbursed may be presented separately. The chapter does not mention patients' own time.
Published rise in cost per life-year saved when patient time is included in colonoscopy screening
Jonas DE, Russell LB, Sandler RS, Chou J, Pignone M. Value of patient time invested in the colonoscopy screening process: time requirements for colonoscopy study. Medical Decision Making. 2008;28(1):56-65. Abstract, which states that including patient time costs would raise the cost per life-year saved with screening colonoscopy by 68%, to USD 22,000 against USD 13,100, and that the rise could lie anywhere in a range of 17% to 224% depending on the time interval valued; the 68% is the same proportional rise as g_ICER here, on cost per life-year saved rather than per QALY (22,000 over 13,100, less 1, is 0.679, derived).
Canonical Identity
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