The standard method to measure quality of life (QoL) is to convert a generic quality of life score to a utility value, thus:
Score on a generic quality of life questionnaire X Conversion factor (tariff) = Utility
The QoL score must be generic because it has to cover all ailments, from deafness to paraplegia to depression.
The conversion factor converts this score to a utility that provides a common 1-0 (best health to death) scale, but also allows for negative values (worse than death). The most commonly used QoL questionnaire is the EQ-5D, which has only five dimensions (mobility, ability to care for oneself, ability to perform usual activities, pain/discomfort, and anxiety/depression). There is reason to question whether this is sufficiently broad for health (narrowly defined) use. For instance, it might not fully capture the utility loss from blindness. If it does not fully capture health narrowly defined, then it may be assumed that it falls shorter still for health more broadly defined to include effects of social care, economic independence, and overall happiness. Scales such as the WALY (Wellbeing-Adjusted Life Years) scale try to capture these outcomes. However, it is cumbersome to have two separate scales; ideally we need one, covering the same dimensions, but without introducing distortions by double counting some of them, but not others. Work is ongoing to sort this all out by collating information on many dimensions and eliminating those that largely duplicate information that others capture more specifically.
Enter Amartya Sen, an economist who won the Economics Nobel Prize in 1998 (alright, technically the Svergies Riksbank Prize in Economic Sciences). He emphasised human capabilities and argued that happiness was not enough – it was more important to have the capacity to understand and appreciate what the world has to offer and to be involved politically, than to simply have a hedonic life. Professor Jo Coast, collaborator of CLAHRC WM, has produced a score called ICECAP-A (ICEpop CAPability measure for Adults) for the purpose of measuring capabilities.
Capability-based measures and patient perceived quality of daily life are fundamentally different constructs and pin-point the fundamental philosophical distinctions that lie at the heart of the quality of care debate. Like Candide in Voltaire’s play, I would gladly sacrifice happiness for an intellectual appreciation of the world and what lies beyond.
— Richard Lilford, CLAHRC WM Director
- Al-Janabi H, Flynn T, Coast J. Development of a self-report measure of capability wellbeing for adults: the ICECAP-A. Qual Life Res. 2012; 21(1): 167-76.