As far as I can tell (both from searching manually and via Claude), none of the RCTs of menstrual cups in low-resource settings have had severe adverse events (see for example https://​​www.thelancet.com/​​journals/​​eclinm/​​article/​​PIIS2589-5370(23)00438-8/​​fulltext, https://​​bmjopen.bmj.com/​​content/​​7/​​4/​​e015429). That’s enough to give some confidence that adverse events are rare, but not enough to really understand what the true rate is (it seems like all studies together cover at most 10000 person-years of menstrual cup usage in low-resource settings, and my understanding is that among e.g. tampon users in high-income countries, rates of toxic shock syndrome are something like 1-3 per 100000 person-years of usage, with risks for menstrual cup users thought to be broadly similar but less certain due to smaller sample sizes). Also, the RCTs have generally involved some kind of hygiene education, which I’m not sure Nick’s $7.5 accounts for.
If the rate of severe complications was 1 per 10000 person-years of menstrual cup usage (which seems at the higher end of what could be theoretically compatible with the evidence we have so far) and women still wanted to use the cups when informed of the risks, that actually wouldn’t change Nick’s BOTEC very much (say an average severe adverse event led to a 15 DALY loss, we have 0.0598-15*7.5/​10000 = 0.04855 DALY/​Cup). Accounting for cup hygiene education costs might be the more meaningful change to the BOTEC, but I don’t think it would change things by more than 50%. That would leave menstrual cups still looking like a potentially promising intervention.
So overall after looking at this, I don’t think that the infection risk concern is a slam-dunk reason against menstrual cups as an intervention. But it seems like if future wellbeing-focused research returned promising results, it would be prudent to fund a big trial that tried hard to monitor for severe adverse events before going to large-scale implementation.
As far as I can tell (both from searching manually and via Claude), none of the RCTs of menstrual cups in low-resource settings have had severe adverse events (see for example https://​​www.thelancet.com/​​journals/​​eclinm/​​article/​​PIIS2589-5370(23)00438-8/​​fulltext, https://​​bmjopen.bmj.com/​​content/​​7/​​4/​​e015429). That’s enough to give some confidence that adverse events are rare, but not enough to really understand what the true rate is (it seems like all studies together cover at most 10000 person-years of menstrual cup usage in low-resource settings, and my understanding is that among e.g. tampon users in high-income countries, rates of toxic shock syndrome are something like 1-3 per 100000 person-years of usage, with risks for menstrual cup users thought to be broadly similar but less certain due to smaller sample sizes). Also, the RCTs have generally involved some kind of hygiene education, which I’m not sure Nick’s $7.5 accounts for.
If the rate of severe complications was 1 per 10000 person-years of menstrual cup usage (which seems at the higher end of what could be theoretically compatible with the evidence we have so far) and women still wanted to use the cups when informed of the risks, that actually wouldn’t change Nick’s BOTEC very much (say an average severe adverse event led to a 15 DALY loss, we have 0.0598-15*7.5/​10000 = 0.04855 DALY/​Cup). Accounting for cup hygiene education costs might be the more meaningful change to the BOTEC, but I don’t think it would change things by more than 50%. That would leave menstrual cups still looking like a potentially promising intervention.
So overall after looking at this, I don’t think that the infection risk concern is a slam-dunk reason against menstrual cups as an intervention. But it seems like if future wellbeing-focused research returned promising results, it would be prudent to fund a big trial that tried hard to monitor for severe adverse events before going to large-scale implementation.