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.




New Answer
New Comment

2 Answers sorted by

First even though the way they are calculated can be very different, in theory at least  I think the DALY should just be opposite of a QALY, so QALYs gained = DALYs averted (in practise roughly) for a given intervention

Thanks so much, I had the same question for my OneDay Health cost-effectiveness post and was unsure what to do.d

  • In the "Doing good better" book they used I think 37.5 QALYs to a life but I'm not sure where they got that from (maybe using age discounting and like you say all life is not lived in good health?)
  • For my OneDay Health calculation to be conservative I used 82 as close to the "global maximum realistic" life expectancy, which is where you take the life expectancy from a country like Hong Kong or Japan and use that. Now it's around 88 I think? The idea is that if every human is valued equally, this is the maximum realistic life expectancy given the best diet, medical care and other factors available 
  • For DALY calculations now WHO uses 92, projecting out to 2050. "The loss function is based on the frontier national life expectancy projected for the year 2050 by the World Population Prospects 2012 (UN Population Division, 2013), with a life expectancy at birth of 92 years."

But with all that said I'm not very helpful as I don't have a clear answer for you ;). I could be wrong but I don't think there's a completely standard way of doing it.

You were rather conservative in choosing 82. It'd be fair to equate averting 82 DALYs to saving the life of a typical newborn and successfully immunizing said newborn from having any medical conditions that reduce their QALYs during their 82-year lifespan.

And of course the "typical" life saved is on average older than a newborn, so has fewer than 82 years of life remaining even before adjusting for DALY effects.

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!

Sorted by Click to highlight new comments since: Today at 8:33 PM

I summarised a little bit how various organisations in the EA space aggregate QALY's over time here.

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 think this post by Open Phil is probably related to what you're asking for and I would also recommend the GiveWell post on the same topic

I think this is still generally seen as a bit of an open question in the space