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The ICECAP (ICEpop CAPability) index is a survey instrument of quality of life. It differs from other commonly used instruments such as the EQ-5D and SF-36 in that it focuses on overall quality of life rather than health-related quality of life and is the first to use best-worst scaling discrete choice experiments to estimate population tariffs. It was originally designed specifically for use in older populations but a version has since been developed for adults that reflects that population's different priorities. The original for older populations is called ICECAP-O while the adult version is called ICECAP-A.

Use

ICECAP scores can be used to measure:
-Changes in QoL from clinical and social service interventions
-Variance in QoL within surveys
-Variance in Qol between populations

Development

"The ICEPOP programme advances the notion of going beyond health in evaluating outcomes in two areas. The first is in relation to the quality of life of older people and the second concerns what older people think is important to them in terms of end-of-life care. In both areas in-depth interviews have been used to understand what is important to older people themselves in terms of these important issues and the BWS approach has been used to obtain values for the resulting quality-oflife index. For understanding the important attributes of quality of life, in-depth interviews were conducted with 40 older people. Discussion during interviews focused initially upon a number of factors that influenced quality of life. These were activities, relationships, health, wealth, surroundings and religion/faith/spirituality. Probing during interviews and further analysis, however, indicated that five conceptual attributes were important.

These were: attachment (feelings of love, friendship, affection and companionship); role (the idea of having a purpose or ‘doing something’ that is valued, either by the individual and/or by others); enjoyment (ideas of pleasure, joy, and a sense of satisfaction); security (ideas of feeling safe and secure, not having to worry and not feeling vulnerable); and control (being independent and able to make one’s own decisions)"

Design

Five conceptual attributes:
1. Attachment (feelings of love,friendship, affection and companionship)
2. Role (the idea of having a purpose or ‘doing something’ that is valued, either by the individual and/or by others)
3. Enjoyment (ideas of pleasure, joy, and a sense of satisfaction)
4. Security (ideas of feeling safe and secure, not having to worry and not feeling vulnerable)
5. Control (being independent and able to make one’s own decisions)

Four levels:
1. None
2. A little
3. A lot
4. All

Example question:

5. Independence (control)

I am able to be completely independent [4]

I am able to be independent in many things [3]

I am able to be independent in a few things [2]

I am unable to be at all independent [1]

Scoring

A completed ICECAP survey produces a "state" that can be expressed in a 5-digit number (e.g. 42332) that sequentially corresponds to the given responses. Thus, the state of "full capability" on each attribute is coded as "44444" while the state of the "absence of capability" is coded as "11111".

ICECAP scores are anchored on a [0 - 1] scale that can be derived from each state by re-scaling the responses, with the "11111" state always scaled to 0 and the "44444" state always scaled to 1. All other states, such as state "33333" will produce an intermediate value (such as 0.866).

The scaling is determined in each population using a best-worst scaling method that determines how much a population values each level of capability for each attribute, as the relative differences between levels may not be linear (i.e. there may be a much greater jump in value between "no capability" and "a little capability" than there is between "a lot of capability" and "all the capability").

Differences between ICECAP-O and ICECAP-A

ICECAP-O is the original instrument designed for use in older populations (65+ y.o.). ICECAP-A is a modified version of ICECAP-O that takes into account the priorities of younger (18 - 64 y.o.) populations. For example, in a preliminary survey of Australians, younger people were found to most strongly value attachment, middle-aged people were found to most strongly value security, and older people were found to most strongly value control.