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Effectiveness of Giving Blood

I believe past discussion about giving blood within EA has undervalues doing so and hopefully the reasoning laid out here will show why.

Some caveats first; I think that some of the reasoning used here may only apply to certain blood groups: i.e. universal donors, additionally past discussion has focused on QALYs and reaches a different conclusion to me - it may be that using different metrics leads to different conclusions or that my method is flawed however due to the limited information about the stats of giving blood and limited discussion within EA (2 posts one against and one for blood donation being effective as far as I can tell) means having a discussion at al could be useful.

My reasoning

  • Each whole blood donation produces 1 unit of blood (~about 1 pint although the exact amount is not important for this argument)[1]
  • About 1/3 of blood donations are used for emergencies[2]
  • I am assuming that in such an emergency the patient would die if they do not receive a blood transfusion
  • When used in an emergency 8-10 units of universal donor blood is used initially[3] (I will use the conservative 10 units going forward)
  • This means a 1 unit donation makes up 10% of the blood used/needed to save a life

Overall this means we have: 1/3 chance of a donation being used in an emergency * a 1/10 contribution to saving a life in the emergency equating to ~1/30 average life saved per donation.

This does not take into account that the 10 units is for the intial 24 hours of transfusions, after which other blood types can be used. This also does not take into account the other 2/3 times where if not saving a life the donation goes on to improve someone's well-being/health. Additionally the concrete information about blood donation and how it is used is lacking and claims about each donation saving up to 3 lives are inaccurate at best and misleading at worst. Furthermore statements of "1/3 of blood is used for emergencies" may be because 1/3 of blood donated is universal and thus 100% of a universal blood donator's blood may be used in an emergency - greatly improving the impact for them; this seems unlikely but these points hopefully show that the 1/30 estimate is likely to be conservative rather than optimistic.

This would make each donation roughly equivalent to a (1/30*5000) $166 donation to the Against Malaria Foundation for maybe an hour of time.







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2024 edit: This is being shared as "you shouldn't donate blood". I think many people should donate blood and it largely depends on your situation, partially for these reasons

Original comment:

Thanks for doing a quantitative estimate, I think it's a very useful exercise and something we should do more often.

I disagree with your main conclusion for two main reasons:

  • As a heuristic, in the UK the NHS values a life at roughly £1M. If an extra blood donation would save 1/30th of a life they would be willing to pay £33k for one, which seems very high.
  • You mention that only a fraction of donated blood is used in emergencies, I would expect that in case of blood shortages the fraction would change, so the counterfactual impact of donating blood is much lower. I think in this case counterfactuals are more useful than Shapley values (Shapley values give the same merit to all actors, counterfactuals consider the difference in value between acting and not acting).

Something that would make me change my mind is an estimate of how many people are dying because of blood shortages. (I would guess close to 0 in rich countries).

As for donating blood in general, I think the costs and benefits are very location specific.
In Italy, you get free blood tests, an extra vacation day, and a nice sandwich, so it's potentially negative cost.

If all need for blood is met regardless of your donation, your counterfactual impact should be 0. Would Shapley values agree? If it gives the same to everyone, it would mean everyone gets 0 impact.

See this other comment
It depends on how you model it. If you model other donors as part of the environment (like e.g. the needle for drawing the blood), everyone gets 0. If you model each donor as an actor they all get. Nuno made http://shapleyvalue.com/ to play around with it

I think in this case counterfactuals are more useful than Shapley values

Could you say why? Or link somewhere that explains the advantages of counterfactuals? I had never heard of Shapley values, but opened the post and read some and immediately thought "oh my god yes!".

Let's say you had $5k to donate and you could donate it to:

  1. An intervention that saves 3 lives, but is 99.9% going to be funded by another donor no matter what you do, and has only room for an extra $5k (if it gets $10k it still only saves 3 lives).
  2. An intervention that saves 1 life, and would otherwise not be funded.

To maximize a naively calculated Shapley value you would choose the first one, even though the second one leads to better outcomes (more lives saved in expected value).

I'm a bit unsure about the general principle and the details, probably there's a way to compute Shapley values that would maximize the expected value in this case as well, but I think it would also apply to the blood donor case.

Very low confidence in this, but I think Shapley values are useful for coordinating strategic agents that act in response to each other, and to avoid double counting, but not when the actions of other agents are not influenced by yours.

This comment on the Shapley values post explains it better

This post might be interesting for some details and proposes some solutions

Thanks. I think I need to dive deeper into the mathematical definition to understand this. It seems to me that counterfactual value is not as well defined.

the second one leads to better outcomes (more lives saved in expected value)

Short objection: it is not necessarily true that higher expected value = better. For example, in this scenario for low enough risk tolerance the first scenario would be better.

one point of criticism if this cost-effectiveness estimate: in high-income countries there is no substantial shortage of blood. In case of acute shortage, blood banks can easily recruit donors. So if you don't donate and that results in a blood shortage of one unit, another donor is likely to step in. If you donate blood, you simply replace the donation: the other donor who would have donated in your place, will not be recruited. Your donation will not be an extra donation. Or in other words: blood donation has low additivity and blood supply is inelastic. The case for plasma might be different, as there is a global plasma undersupply. A plasma donation will not simply be a replacement of someone else's donation. But I don't know how many QALY's you save by donating plasma. 

I have an example for you: high-income country germany:

  1. Germany has frequent blood-shortages, that lead to less planned operations or even no blood for urgent operations- every donor can at least safe life quality or even lifes in that periods of time
  2. In Germany one donation can be stored up to 42 days (or much less) - there is limited recruitment time, if storage is low.
  3. Over 12 % of the germans, that can donate blood, do so - there are just roughly 7 replacement people per donor
  4. many blooddonations are devided in their different parts - blooddonations are also plasmadonations with added material for other usecases

1: But how do you know when there is an acute blood shortage, when it is time for you to donate with high impact? You only know it when a blood bank actively communicates about it in order to increase donations, but then other potential donors will also be informed and become motivated to donate blood. Cfr blood shortage in New York after 9/11,  donors were recruited by mass advertisement, and quickly there was an oversupply of blood. It is like on the stock market: if you don't buy a share, someone else will, and it is difficult to know the good time when to buy or sell.

4: blood donation is not an effective means to collect blood parts such as protein that are in plasma, because the rest of the blood (e.g. the red blood cells) is waste. You can donate plasma more frequently. Plasma has a longer shelf life, can be traded internationally,... That means in general there is a chronic (global and local) undersupply of plasma (and plasma derived products), but no chronic undersupply of blood in high-income countries. 

I really like these kinds of write-ups that provide a rough calculation of the cost-effectiveness of altruistic actions! A point I would like to poke at is the conclusion that if there's a 1/3 chance of your blood being used in a (fatal) surgery, you should attribute 1/3 * your share of the blood used of a life saved. This isn't counterfactual reasoning, which I think is the best way to go about analyzing this. When deciding, on the margin, whether I should donate blood or not, I should try to figure out what the expected consequences are if I donate as compared to me not donating.

My guess is that, in developed countries, it's extremely rare that people die during surgery because of a lack of blood units available at the hospital.

certain blood groups

Maybe worth having blood drawn once and then reassessing based on personal blood, especially in light of exceptional cases like:


If using counterfactual reasoning, should we consider what the alternative to giving blood would be? Is it likely to be an hour of effective work or earning-to-give? For me it is not, as giving blood displaces otherwise unproductive time.

Thanks for doing the back of the envelope calculation here! This made me view blood donation as significantly more effective than I did before. A few points:

  • Your second source doesn't exactly say that one third of blood is used during emergencies, but rather that 1/3rd is used in "surgery and emergencies including childbirth". Not all surgeries are emergencies, and not all emergencies are potentially fatal.
  • However, I think this is more than balanced out by the fact that according to the same source, the other two thirds are used to treat "medical conditions including anemia, cancer, and blood disorders." A lot of those conditions are potentially fatal, so I think it probably actually ends up at more than 1/3rd of blood donated going to life-saving interventions.

I'd love to see someone do the full calculation sometime. Based on this, I expect that for a lot of people, donating blood is sufficiently effective that they should do it once in a while, even instead of an hour of effective work or earning-to-give.

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