Many health economists rely on the concept of a quality-adjusted life year (QALY) to measure the value of different treatments. When comparing one treatment to another, one can summarize the health benefits based on not only the among of life that was extended (i.e., extra years lived) but also what the quality of life is. QALYs take into account both survival improvements and improvements in quality of life. Most QALY measures, however, are based on EQ-5d surveys which measure the extent that each person is mobile, can care for themselves, is able to do their usual activities, has any pain or discomfort, and has any anxiety or depression.
QALYs are problematic for a number of reasons. For instance, health economists often treat QALY improvements as equally valuable for all people. For instance, a 1% improvement in quality of life (say 0.01 QALY) for a treatment for 100 people would be just as valuable as a treatment that added 1 year of extra life in full health (1 QALY), even though most people would think that an extra year of life in full health is more valuable than a small health gain for many people.
Additionally, QALYs typicaly measure your health status, but are don’t really measure what people are capable of doing. To address this short coming, a paper by Flynn et al. (2015) proposes the use of Investigating Choice Experiments Capability Measure for Adults (ICECAP-A). This measure is based on 5 attributes, each of which are scored between 1 to 4 ranging from full capability to no capability. The attributes include:
Stability: being able to feel settled and secure
Attachment: being able to have love, friendship and support
Autonomy: being able to be independent
Achievement: being able to achieve and progress
Enjoyment: being able to have enjoyment and pleasure
One survey by Flynn et al. (2015) in the UK found that:
The ‘best’ data indicate very strong relative preferences for stability and attachment, with autonomy being the third most important attribute. The ‘worst’ data suggest strong aversion to low levels of attachment and enjoyment. Achievement does not appear to have a large impact upon best or worst preferences.
On the one hand, these items probably do a much better job of measuring quality of life. On the other hand, many of these attributes can been internally determined and affected by attitude in addition to health state whereas QALYs are based much more on functional status (e.g., pain, mobility) rather than capabilities. Patients themselves may prefer ICECAP, but likely clinicials and researchers prefer QALYs; the former may do a better job at capturing quality of life but the latter may better capture changes in quality of life between two different treatments.
- Flynn, Terry N., Elisabeth Huynh, Tim J. Peters, Hareth Al‐Janabi, Sam Clemens, Alison Moody, and Joanna Coast. “Scoring the Icecap‐a Capability Instrument. Estimation of a UK General Population Tariff.” Health Economics 24, no. 3 (2015): 258-269.