Information obtained from the ICECAP measures can be combined with time.  The theoretical basis for doing this is, however, quite different from the basis for the standard health economic tool of Quality-Adjusted Life-Years.  In QALYs, the aim is to adjust life-years for the health state experienced within those life years by multiplying health states by length of time in that state.  The theoretical basis for this arises from the valuation of health states against death which is assumed to be a health state with a value of zero; this then enables life-years to be adjusted for quality, with years of death having a quality-adjustment value of zero.

ICECAP measures can be combined with time to generate Years of Full Capability (YFC) (equivalent).  These represent the total amount of capability that is available over time and more information about this and other measures is given below.  In this measure, capability is valued in relation to full capability and no capability.  The treatment of death in this paradigm is through its measured impact on capability, rather than through a capability value associated with death.  Those who die have no capability; thus a person who dies would have zero years of full capability from this point of death.  The YFC approach only measures capability within the capability space; the use of a zero value for death is based on measured lack of capability, rather than any judgement about the value of any capability state in relation to death.  Instead the judgement of states of capability is made in relation to states of no capability, of which death might be one. 

This represents an important conceptual difference between the theoretical basis for the QALY measure, commonly used in health economics, and the theoretical basis for Years of Full Capability (equivalent) and it is important that those using the two measures understand this conceptual difference.  

In health economic analysis, there is a reliance on having decision rules in place so that it can be judged as to whether one course of action (e.g. Intervention A) should be taken over another (Intervention B). The standard framework for this in health economic evaluations is to maximise health (more specifically quality-adjusted life years or QALY gains), so long as the cost of the QALY gains fall below a willingness to pay threshold. For example, the UK regulatory body NICE, use a cost-effectiveness threshold of £20,000 to £30,000 per QALY gain. The rationale behind such thresholds is that they are based on a social willingness to pay estimate, or alternatively a reflection of the opportunity costs forgone by providing a new intervention.

In terms of decision-rules for use in relation to ICECAP, there are a number of factors that need to be considered.

1. What is the overall objective when measuring capability?
2. What is the outcome of interest to achieve this objective?
3. What is the cost-effectiveness threshold for achieving the objective as efficiently as possible? 

1. The overall objective in health economics tends to follow that used within welfare economics, in terms of maximising the outcome of interest, irrespective of distributional considerations. As the capability approach offers an alternative normative framework to welfare economics, it is unclear whether adopting such a maximisation approach is always appropriate. A recent literature review examined how practical applications of the capability approach were undertaken and although there were some studies applying a maximising criteria, the majority of studies employed an objective below that of what could be fully attained (Mitchell et al. 2016). This led to the development of an alternative objective for economic evaluations known as sufficient capability (Mitchell et al. 2015).

(Continued in Part 2 below)

2. In terms of outcome of interest when using the ICECAP, two approaches have been put forward. The use of Years of Full Capability (YFC) (equivalent) works similarly to that of the traditional approach taken in health economics of measuring the absolute gains across time (Flynn et al. 2015). It is important to note, however, that this outcome is NOT equivalent to a QALY outcome: the anchors on the ICECAP values are on a full capability-no capability scale (1-0), whereas for measures used to generate QALYs, they are anchored on a perfect health-dead scale (1-0).  Years of full capability (equivalent) represent the total amount of capability that is available over time; those who die have no capability and thus would have zero years of full capability from this point of death.  The YFC approach only measures capability within the capability space; the use of a zero value for death is based on measured lack of capability, rather than any judgement about the value of any capability state in relation to death.  This is an important conceptual difference from the theoretical basis for the QALY measure commonly used in health economics, where values are generated in relation to the value for death (which is commonly set at zero). 

An alternative approach is to generate Years of Sufficient Capability (YSC), whereby the change in capability over time is based on the relative changes below a threshold, deemed to be sufficient (Mitchell et al. 2015).

3. What a sufficient level of capability is, and how much the general public are willing to pay for a YFC and YSC, have now been estimated in the UK for the ICECAP-A (Kinghorn, 2019; Kinghorn, 2021).

The ICECAP measures are proposed as a way of measuring outcomes in a growing number of national guidelines for economic evaluation.

• The UK National Institute for Health and Care Excellence guidelines on social care highlight, in the reference case, that ICECAP measures can be used to measure and value capability outcomes:

https://www.nice.org.uk/process/pmg20/chapter/incorporating-economic-evaluation

• The UK Social Care Institute of Excellence discuss the use of ICECAP as one way of valuing the outcomes of social care interventions: 

http://www.scie.org.uk/publications/reports/report52.asp

• Zorginstituut Nederlands (Dutch Care Institute) highlight ICECAP as a measure that can be used alongside the QALY in the economic evaluation of long-term care:

https://english.zorginstituutnederland.nl/publications/reports/2016/06/16/guideline-for-economic-evaluations-in-healthcare

Mitchell PM, Roberts TE, Barton PM, Coast J. Applications of the Capability Approach in the Health Field: A Literature Review. Social Indicators Research. 2016:1-27.

Mitchell PM, Roberts TE, Barton PM, Coast J. Assessing sufficient capability: A new approach to economic evaluation. Soc Sci Med. 2015;139:71-9.

Flynn TN, Huynh E, Peters TJ, Al-Janabi H, Clemens S, Moody A, et al. Scoring the Icecap-a Capability Instrument. Estimation of a UK General Population Tariff. Health Econ. 2015;24(3):258-69.

Kinghorn P. Using deliberative methods to establish a sufficient state of capability well-being for use in decision-making in the contexts of public health and social care. Social Science & Medicine 2019;240:112546. doi: https://doi.org/10.1016/j.socscimed.2019.112546

Kinghorn P, Afentou N. Eliciting a monetary threshold for a year of sufficient capability to inform resource allocation decisions in public health and social care. Social Science & Medicine 2021;279:113977. doi: https://doi.org/10.1016/j.socscimed.2021.113977