A quality-adjusted life year (QALY) is a commonly used unit of currency to assess the value of medical interventions. A person who lives a year in perfect health equates to 1 QALYs, a person with bad hayfever for a year might equate to 0.999 QALYs, while a person with moderate-to-severe depression might equate to 0.5 QALYs. Being dead for a year equates to 0 QALYs.
QALYs are mostly used to compare the value of different interventions. For example, $50 of antibiotics for a serious infection that keeps someone alive and in good health when they otherwise would have died generates many QALYs, while an expensive anticancer drug that expands low-quality lifespan by only a few months might be worth only a fraction of a QALY. In this case, if we had a limited budget, we would spend it on the antibiotics over the chemotherapeutics to get more QALYs for our bucks.
What I've been unable to find anywhere in the literature is how many QALYs a typical human life equates to? If I save a newborn from dying, is that worth 70 QALYs (~global life expectancy), 50 QALYs (not all of life is lived in good health), or some other value? I presume there must be a value used by governments or academics used somewhere, but I can't find it. Does anyone know, or could explain where I might find it? Thanks!
P.S. I am aware that there are many other metrics used as well, such as disability-adjusted life years (DALYs) by the WHO, value of a statistical life (VSL), or 'deaths averted' by Givewell and others.
There's no single right answer here, and several good approaches depending on the application to which you want to put the information. A reasonable estimate is that a baby born today and then given the best life modern society can give it will accrue around 24 QALYs (at a 3.5% discount rate). This is equivalent to 70 undiscounted QALYs, but you absolutely must discount to some extent in this case, because a QALY now is clearly preferred to a QALY in 80 years time.
This value is found by multiplying the life expectancy of a baby born in the UK in 2020 by the typical quality of life that baby will experience each year of their life. Life expectancy is pretty straightforward to calculate (I take it from the Office for National Statistics), quality of life is much more complicated - the standard in the field is Ara, R. and Brazier, J.E. (2010), but this is getting a bit out of date now. https://eprints.whiterose.ac.uk/11177/1/HEDS_DP_10-11.pdf
Obvious problems with the translatability of this approach is that the Ara & Brazier paper only applies to the UK. Different countries will have different profiles of population health (which is obvious) and also different ways of interpreting how health applies to QALYs (which is less obvious). For example, if old age affects your ability to walk easily / comfortably then this might matter more to your QALYs in dense walkable European cities than car-focussed American suburbs (I have no idea if this mechanism is true, just giving it as an example). This will be particularly challenging if you're trying to calculate the number of QALYs a person accrues in a global health context, because there is limited research in the area.
Thanks! The link to Ara & Brazier (2010) is particularly helpful, as Figure 1 contains the information I need to calculate it for at least a UK citizen.
UK life expectancy is ~80. Eyeballing the figure suggests those <30 accrue ~0.95 QALYs/year, while those from 30-80 accrue ~0.85. Putting that together would suggest ~71 undiscounted QALYs, which agrees with your estimated of 70.
I'm aware that this is an extremely crude and rough way of doing things, but it's still helpful as a sanity check for the problem I'm currently working on. Thanks again!