Authors: Andrés Gómez-Emilsson and Alfredo Parra-Hinojosa

Summary

Kidney stones cause an immense amount of suffering worldwide. Weighted by their intensity, and depending on some assumptions, we posit that kidney stones may account for a large fraction of human suffering worldwide. Finding cost-effective solutions for this hedonic catastrophe should be a very high priority in any suffering-focused research agenda.

While researching kidney stone pain, we were very impressed with the online reports of patients using chanca piedra (Phyllanthus niruri) to treat their pain and prevent the formation of stones, so we decided to take a closer look. Given the limited number of high-quality studies on the efficacy of chanca piedra, we decided to look for additional evidence online and collected thousands of WebMD, Amazon, and Reddit reviews about chanca piedra and other kidney stone treatments, and classified them along a few dozen different dimensions (such as reported side effects, reported pain reduction, etc.).

While we acknowledge that internet reviews are not usually a reliable source of information concerning medical matters, we also make the case that the reviews of chanca piedra in particular should not be dismissed out of hand. In particular, we find that chanca piedra:

1. Is effective for an exceptionally high percentage of people, judging by both the star ratings and review contents.
2. Has an exceptionally low rate of reported side effects.
3. Has high-quality reviews, judged by criteria such as providing adequate context and believable narratives consistent with kidney stone experiences.
4. Is supported by reviews that are equally very positive across WebMD, Amazon, and Reddit.
5. Compares very favorably to the WebMD reviews of standard prescription medications for kidney stones, including: tamsulosin (aka Flomax), allopurinol, potassium citrate, and hydrochlorothiazide.
6. Has a far lower rate of reported side effects and a higher rate of effectiveness than melatonin and ashwagandha, two widely used over-the-counter supplements generally recognized as safe and effective, which we include as a sanity check.
7. Is likely an effective prophylactic based on the reviews by those who report to be using it as such. This is perhaps one of the most significant aspects. We get the strong impression that chanca piedra is more effective as a preventative medicine than a source of acute relief. This, along with the unusually low rate of side effects reported, is what motivates us to explore its use in preventative medicine as a possible philanthropic cause area.

We address the epistemological concerns around updating one’s sense of how promising chanca piedra is based on internet reviews, and argue that the most likely reasons for such high ratings possibly being fake do not seem consistent with the whole picture so far. In particular, we argue that:

1. These reviews are consistent with the current scientific literature: Stones can indeed dissolve or become smoother, and patients taking chanca piedra also report exceptionally low rates of side effects.
2. Our observations are inconsistent with astroturfing, primarily because of the general lack of emphasis on specific brands in the reviews and, secondarily, due to the consistency of reviews across brands and methods of consumption.
3. Selection effects do not seem to be strong enough to explain away these reviews: It is true that both exceptionally good and exceptionally bad responses to a treatment or supplement motivate people to write reviews. That said, this seems inconsistent with the lack of side effects reported. Although selection effects should make us very cautious when interpreting the absolute base-rate of specific effects, contrasting such base-rates across the reviews of various treatments is valuable information that controls (to a large extent) for selection effects.

We also discuss what we can do about this, why chanca piedra does not yet appear on official sites, and how we envision a way for this intervention to significantly reduce extreme pain worldwide.

Following the ITN framework, kidney stones are clearly important due to the scope and severity of the suffering. While it may seem that kidney stones are not a neglected problem, we argue that there is at least an epistemological angle that is neglected. And if we do find cheap solutions that are both medically safe and highly effective at reducing the enormous amount of suffering associated with this condition, the problem also becomes much more tractable.