Blood Donation: (Generally) Not That Effective on the Margin

[Note: This originally came out of a post on the Facebook group, which was then reversed in light of Gregory Lewis's expert comments. The substance of this article is his; any errors are mine.]

If no one donated blood, a lot of trauma/hemorrhage victims would die, and the world would be a lot worse off. The average unit of blood donated goes pretty far, in terms of the expected value of the good it does. However, when considering whether or not to donate, we need to evaluate the counterfactual difference our actions make. That is, rather than looking at the average donation, the relevant measurement is of the marginal donation. This brings up the following considerations:

1) As it stands, a substantial number of people already donate regularly, and will continue to do so whether or not the (comparatively tiny) EA community does too.

2) Truly life-or-death situations are a minority of transfusions, and these are pretty much already covered by the existing supply. In fact, hospitals almost always keep an emergency reserve of O- specifically for these cases, so it's very rare that someone directly dies for lack of compatible blood. Because a large number of transfusions/donations happen each day, and blood product can often be transported to different hospitals to meet local shortages, projected supplies are relatively easy to forecast within a given margin of error, so it is possible for hospitals to maintain this emergency supply to handle urgent cases.

Thus, the effect of an additional donation to the existing supply is to help cases where the patient wouldn't be directly saved from death, but a transfusion would improve the quality of their recovery. Nailing down exactly how many QALYs this typically adds is very difficult to track, and probably hasn't been done in a rigorous way. However, there is reason to believe this number is not that high.

In the UK, a unit of red blood cells (RBCs) costs about 120 pounds. While financial incentives don't translate seamlessly into extra donations, this is roughly this price at which more supply can be obtained, so it roughly reflects the medical field's impression of how valuable it would be to do more outreach per unit. Furthermore, the typical cutoff for whether to fund treatment is ~20,000 pounds/QALY, which is much less efficient than the ~130 pounds/QALY one can get by donating to the AMF. (For more detail on these numbers, see this guesstimate and this explanation of it.)

Thus, for blood donation to be anywhere near as effective as the AMF (in terms of paying 120 pounds/unit for more product), the medical field would have to be undervaluing the effectiveness of blood donations by 2 orders of magnitude. Despite the lack of rigorous calculations done in the literature, a collective miscalculation of this magnitude seems implausible given the feedback mechanisms which exist in medicine, not to mention the tacit knowledge hematologists have developed from making these tradeoffs.

The role of effective altruism is to look for, and seize upon, moral opportunities that have been unfairly passed over by society at large. GiveWell-recommended charities, for instance, may sometimes get positive comments from economists, but receive insufficient funding to fully exploit the ethical gold mine that is their cause area. In the case of blood donations, the medical field generally has ways of spotting and filling in the cheap and obvious ways to save more lives, so our time is better spent on causes that aren't being watched over as carefully.

That said, there are occasional cases where emergency supplies dwindle. When this happens, specific appeals are made, and in these cases it probably is effective to lend some helping hemoglobin. Less crucially, regular donors often drop out on holidays and during the winter (due to colds/flu), so if one is inclined to donate, those are the best times to do so.

Comments (6)

Comment author: Paul_Christiano 06 August 2017 06:38:41PM *  5 points [-]

This seems to confuse costs and benefits, I don't understand the analysis. (ETA: the guesstimate makes more sense.)

I'm going to assume that a unit of blood is the amount that a single donor gives in a single session. (ETA: apparently a donation is 0.5 units of red blood cells. The analysis below is correct only if red blood cells are 50% of the value of a donation. I have no idea what the real ratio is. If red blood cells are most of the value, adjust all the values downwards by a factor of 2.)

The cost of donating a unit is perhaps 30 minutes (YMMV), and has nothing to do with 120 pounds. (The cost from having less blood for a while might easily dwarf the time cost, I'm not sure. When I've donated the time cost was significantly below 30 minutes.)

Under the efficient-NHS hypothesis, the value of marginal blood to the healthcare system is 120 pounds. We can convert this to QALYs using the marginal rate of (20,000 pounds / QALY), to get 0.6% of a QALY.

If you value all QALYs equally and think that marginal AMF donations buy them at 130 pounds / QALY, then your value for QALYs should be at most 130 pounds / QALY (otherwise you should just donate more). It should be exactly 130 pounds / QALY if you are an AMF donor (otherwise you should just donate less).

So 0.6% of a QALY should be worth about 0.8 pounds. If it takes 30 minutes to produce a unit of blood which is worth 0.6% of a QALY, then it should be producing value at 1.6 pounds / hour.

If the healthcare system was undervaluing blood by one order of magnitude, this would be 16 pounds / hour. So I think "would have to be undervaluing the effectiveness of blood donations by 2 orders of magnitude" is off by about an order of magnitude.

The reason this seems so inefficient has little to do with EA's quantitative mindset, and everything to do with the utilitarian perspective that all QALYs are equal. The revealed preferences of most EA's imply that they value their QALYs much more highly than those of AMF beneficiaries. Conventional morality suggests that people extend some of their concern for themselves to their peers, which probably leads to much higher values for marginal UK QALYs than for AMF beneficiary QALYs.

I think that for most EAs donating blood is still not worthwhile even according to (suitably quantitatively refined) common-sense morality. But for those who value their time at less than 20 pounds / hour and take the numbers in the OP seriously, I think that "common-sense" morality does strongly endorse donating blood. (Obviously this cutoff is based on my other quantitative views, which I'm not going to get into here).

(Note: I would not be surprised if the numbers in the post are wrong in one way or another, so don't really endorse taking any quantitative conclusions literally rather than as a prompt to investigate the issue more closely. That said, if you are able to investigate this question usefully I suspect you should be earning more than 20 pounds / hour.)

I'm very hesitant about EA's giving up on common-sense morality based on naive utilitarian calculations. In the first place, I don't think that most EA's moral reasoning is sufficiently sophisticated to outweigh simple heuristics like "when there are really big gains from trade, take them" (if society is willing to pay 240 pounds / hour for your time, and you value it at 16 pounds per hour, those are pretty big gains from trade). In the second place, even a naive utilitarian should be concerned that the rest of the world will be uncooperative with and unhappy with utilitarians if we are less altruistic than normal people in the ways that matter to our communities.

Comment author: Austen_Forrester 06 August 2017 07:13:05AM 1 point [-]

I think it may be useful to differentiate between EA and regular morals. I would put donating blood in the latter category. For instance, treating your family well isn't high impact on the margin, but people should still do it because of basic morals, see what I mean? I don't think that practicing EA somehow excuses someone from practicing good general morals. I think EA should be in addition to general morals, not replace it.

Comment author: DonyChristie 06 August 2017 03:16:42PM *  0 points [-]

I'm curious what exactly you mean by regular morals. I try (and fail) to not separate my life into separate magisteria but rather seeing every thing as making tradeoffs with every other thing, and pointing my life in the direction of the path that has the most global impact. I see EA as being regular morality, but extended with better tools that attempt to engage the full scope of the world. It seems like such a demarcation between incommensurable moral domains as you appear to be arguing for can allow a person to defend any status quo in their altruism rather than critically examining whether their actions are doing the most good they can. In the case of blood, perhaps you're talking about the fuzzies budget instead of the utilons? Perhaps your position is something like 'Regular morals are the set of actions that, if upheld by a majority of people, will not lead to society collapsing and due to anthropics I should not defect from my commitment to prevent society from collapsing. Blood donation is one of these actions', or this post?

Comment author: Austen_Forrester 06 August 2017 11:43:41PM 0 points [-]

By regular morals, I mean basic morals such as treating others how you like to be treated, ie. rules that you would be a bad person if you failed to abide by them. While I don't consider EA superorogatory, neither do I think that not practicing EA makes someone a bad person, thus, I wouldn't put it in the category of basic morals. (Actually, that is the standard I hold others to, for myself, I would consider it a moral failure if I didn't practice EA!) I think it actually is important to differentiate between basic and, let's say, more “advanced” morals because if people think that you consider them immoral, they will hate you. For instance, promoting EA as a basic moral that one is a “bad person” if she doesn't practice, will just result in backlash from people discovering EA. No one wants to be judged.

The point I was trying to make is that EAs should be aware of moral licensing, which means to give oneself an excuse to be less ethical in one department because you see yourself as being extra-moral in another. If there is a tradeoff between exercising basic morals and doing some high impact EA activity, I would go with the EA (assuming you are not actually creating harm, of course). For instance, I don't give blood because last time I did I was lightheaded for months. Besides decreasing my quality of life, it would also hurt by ability to do EA. I wouldn't say giving blood is an act of basic morality, but it still an altruistic action that few people can confidently say they are too important to consider doing. Do you not agree that if doing something good doesn't prevent you from doing something more high impact, than it would be morally preferable to do it? For instance, treating people with kindness... people shouldn't stop being kind to others because it won't result in some high global impact.

Comment author: RandomEA 05 August 2017 08:34:38PM 1 point [-]

One possible benefit of blood, kidney, and bone marrow donations is that they could demonstrate that EAs actually do care about other people in their country (which could help with movement building), but such donations can only be associated with EA if they are in fact effective on the margin (which does not seem to be the case with blood donations).

Comment author: Brian_Tomasik 06 August 2017 09:56:53AM 0 points [-]

You could put blood donation into the "relaxation" or "fun social activity" category.