Astonishingly, demand for circumcisions is lower than expected

"Just lie back and think of the average treatment effect"

“But wait, look at the treatment effect results”

Thanks to three randomised controlled trials held in several sub-Saharan countries, it is now fairly clear that male circumcision leads to a sizeable reduction in the probability that a man will go on to contract HIV. The treatment effect of getting snipped is nothing to laugh at: most estimates put it at a 50-60% reduction in risk. I’m not sure that anyone has actually ever bothered to do a cost-benefit analysis, but as a policy it seems like a no-brainer to the global health community, who has been quick to support it as an effective means of battling the AIDS epidemic.

Like with most `new’ technologies which have been shown to be effective in a near-laboratory setting, the next step was to roll-out and scale up the intervention. Circumcision campaigns with very ambitious targets kicked off in several SSA countries, many of them supported by PEPFAR. Several years down the road, it seems that many countries are struggling to get anywhere near their goals, as is the case with Swaziland, where only 20% of the targeted demographic were `reached’.

Surprise, surprise, the biggest issue seems to be that of low demand: men in Swaziland don’t appear to be particularly keen to forfeit their foreskin, for a host of reasons, ranging from personal doubts over efficacy, to concerns over pain, to worries about witchcraft:

“That’s also what I wanted to know, and they wouldn’t tell me – what happens to my foreskin once it is cut off?” said Mduli. 

Health Minister Xaba alluded to this when he told the Times of Swaziland, “Some men feared that the foreskin could end up in wrong hands, being used by some unscrupulous people for their ulterior motives.”

The lack of coverage in the Swaziland campaign seems to be indicative of similar campaigns in Kenya, Uganda and Zimbabwe: there is initially a surge in demand as large groups of exceptionally-enthusiastic men line up to be circumcised (similar to the zeal that the Merry Men in Robin Hood: Men in Tights show before Rabbi Tuckman reveals to them what circumcision actually is), but eventually demand levels off and most of the population remains untreated.

This problem isn’t unique to circumcision – there are a lot of `treatments’ which have shown to be effective using rigorous methods, but have failed to scale due to lack of demand. Unfortunately, most randomistas (rightfully) spent there time trying to establish that treatment effects exist before worrying about treatment demand, but then fail to spend as much time figuring out how these things should be rolled out; although sometimes both questions can – to some extent – be answered at once if we are randomly inducing people to take up a treatment, rather than randomising the treatment itself. These questions are not only important for a policy perspective, but they might also give us more insight as to what the actual real or perceived benefits are once we move out of the experimental setting.

Circumcision is a particularly difficult area in this regard. We know very little about how to increase demand for circumcision. Can you tell me what a man’s marginal willingness-to-sell a foreskin is? It is also a difficult subject to cover dispassionately – I suspect that for the already-circumcised, the marginal willingness-to-pay for a foreskin is closer to zero. For many of the uncircumcised, the marginal willingness-to-pay  keep one’s foreskin is probably very, very high. Given the extensive roll-out of circumcision programmes in southern Africa, there will be some incentives to experiment with ways of creating demand here. For example, Berk Ă–zler at the World Bank has suggested that it might be time to start paying men to get circumcised (or at least  begin compensating them for lost wages).

Yet, this brings us to the second problem with the roll-out of circumcision programmes as well as the different methods campaigns might employ to entice men onto the chopping block. We know that, within a relatively short time frame, circumcision significantly reduces a man’s chance of contracting HIV. Yet we know substantially less about how subsequent behaviour might play a role in overall HIV risk down the road. Many have been concerned about Peltzman effects, the tendency for people to do more of an activity when it becomes (what the medical literature is calling behaviour risk compensation). As some have pointed out, even if circumcised men don’t increase their sexual activity enough to offset the effects of circumcision, the effect of transmission on women (who are not protected by male circumcision) will go unmitigated. There hasn’t been nearly enough work done on the behavioural effects of circumcision, but at least one paper, which I wrote about some time ago, has suggested that Peltzman effects are, on average, not a problem. However, the same paper found a bifurcation in behaviour: men who had been circumcised AND believed in the treatment effect reduced their risky sexual behaviour, but those who had been circumcised and did not believe in its effectiveness increased their risky sexual behaviour.

Consider this result in light of some of the proposed methods to get more men circumcised: methods which do not actually involve changing beliefs, such as paying people to get circumcised, might lead to more men who don’t believe in the power of the snip signing up, precisely the men who will end up increasing their risky sexual behaviour. This is quite scary.

I’ve written before about how I’m deeply sceptical about the success of mass-circumcision campaigns. However, even a sceptic wants things to be done right if they’re going to be done at all. It shouldn’t be so astonishing that most men aren’t dashing to the clinic to receive a circumcision. The global health community will need to do more rigorous research on how to get men into clinics, but at the same time that research should be leveraged to make sure that these campaigns are having their intended impact.

The skin I live in

What if offering people protection makes take bigger risks?

OK – it has been a worthwhile break. Let’s do this.

Ever since a spate of randomized controlled trials revealed that circumcision can functionally reduce a man’s chance of contracting HIV, global health officials have been been pushing mass circumcision campaigns as much as possible in sub-Saharan Africa. Concerned that the assumption that the internally-valid results from the RCTs may not hold in `the real world’, I wrote a fairly critical post a few years ago. My main concern was that no one was properly accounting for post-treatment behavioural changes.

I was particularly worried about something called the Peltzman effect, a concern that economists have about offsetting behaviour: if you reduce the riskiness of a particular activity for someone, then they have an incentive to do that activity more. While academics have had some trouble reliably identifying Peltzman effects in the real world, it is still a valid concern: while those undergoing an experimental treatment may not change their behaviour before more information on the effectiveness of that treatment is known, men who know that circumcision reduces their chance of contracting HIV might react by simply having more sex.

Someone has finally taken a look at this – Nicholas Wilson, Wentao Xiong and Christine Mattson have a paper specifically looking for the Peltzman effect in a group of Kenyan men who participated in one of these RCTs. They subdivide the sample based on their pre-treatment beliefs on the effectiveness of circumcision, then look at risky sexual behaviour in two follow-ups six and twelve months later. The punchline?

Contrary to the presumption of risk compensation, we find that the response due to the perceived reduction in HIV transmission appears to have been a reduction in risky sexual behavior. We suggest a mechanism for this finding: circumcision reduces fatalism about acquiring HIV and increases the salience of the trade-off between engaging in additional risky behavior and living longer. We also find what appears to be a competing effect that does not operate through the circumcision recipient’s belief about the reduction in the risk of acquiring HIV.

At first glance, this sounds like good news: those who said they believed that circumcision was effective reduced their risky behaviour – the exact opposite of what one would expect from a Peltzman-type relationship. Wilson et al. chalk this up to a sort-of income effect: now that their baseline risk of contracting HIV is lower (therefore raising potential life expectancy), subjects who have been circumcised decide to invest more in life quality, avoiding dangerous behaviours.

But wait – this nugget of good news is actually obscuring something else: those who didn’t believe that circumcision worked increased risky sexual behaviour – they were less likely to use a condom during intercourse and had more sexual partners. The authors don’t have any good explanations for this behaviour, other than suggesting that being circumcised might make men more attractive to other women, since it signals that they have a lower chance of having HIV. I’m not sure how plausible this is, unless men are making their circumcision status public, this is the sort of information that is usually only revealed very, very late in the game. How could we get around this? Randomly reveal men’s circumcision status (sounds fun, but unethical – these two sometimes go hand in hand)?

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