I care about net benefit. For that you not only need to show that you are reducing mortality by a specific cause but you also need to show that you aren’t increasing mortality through other mechanisms.
If you remove polyps that could develop into cancer, you can reduce cancer incidence, just like you can reduce breast cancer by simply amputating all breasts preemptively. That doesn’t mean that the procedure of the amputating all breasts preemptively has a positive effect on lifespan even when it reduces your breast cancer incidence.
The procedural mortality from colonoscopy is well-characterized at roughly 0-1 deaths per 10,000 (NordICC saw zero in 12,574).
The per-protocol CRC mortality reduction was 15 [7-22] per 10,000 absolute. So even at the low end of the CI, known procedural harms eat at most ~15% of the benefit.
For the net to come out neutral or negative, you’d need an unidentified mechanism of death an order of magnitude larger than every characterized harm. Theoretically unfalsified, yes, but not actually how one should reason about established procedures.
Take for example appendectomy, there’s no powered ACM RCT of appendectomy vs no treatment either, and there never will be (although appendectomy vs antibiotics is very much on the table, other issue!).
The ‘cause-specific reduction doesn’t prove ACM benefit’ idea is usually fine imo, and applies in cases like PSA screening or mammography in 40-year-olds, where the cause-specific benefit is small, overdiagnosis is large, and downstream treatments carry meaningful mortality. Colonoscopy isn’t structurally that case: the cause-specific benefit is large in relative terms, polypectomy harms are well-mapped and small, and removing adenomas isn’t analogous to treating overdiagnosed prostate cancer with prostatectomy.
Pattern matching from one to the other doesn’t work. For similar reasons, the breast analogy doesn’t hold so well.
Take for example appendectomy, there’s no powered ACM RCT of appendectomy vs no treatment either, and there never will be (although appendectomy vs antibiotics is very much on the table, other issue!).
Medicine did use to do appendectomy routinely in people without specific problems with the appendix if there was an operation in that general area and it’s generally believed that this was bad so clinical guidelines changed.
polypectomy harms are well-mapped
I have no reason to believe that’s the case. Just because you well-mapped the area under the streetlamp in search for your key does not mean that you have generally well-mapped the locations where your key might be. The harms that are well mapped are those that show serious clinical signs shortly after the intervention. If you for example take depression due to major head trauma you can only see half of the cases after three months. Delayed effects are a thing. If a treatment increases the lowest nightly heartrate by 5 points that wouldn’t show up as a serious clinical sign in standard medical studies but it would still be a pretty significant side effect that increases mortality.
We do have fairly large amount of lower back pain that’s unexplained by standard medicine. This is because we have a relatively poor understanding and fascia and a few other mechanisms. Osteopaths have a good understand that scars in general can create problems for bodily organization. Besides the scars you probably also have more inflammation and trauma where the effects are poorly mapped.
If you take appendectomy, the effects of the scar that are still perceivable decades afterwards in bodily organization with regards to tension, are not well-mapped. I don’t have any hands-on experience with effects of polypectomy, but I think it’s plausible to have similar issues.
I care about net benefit. For that you not only need to show that you are reducing mortality by a specific cause but you also need to show that you aren’t increasing mortality through other mechanisms.
If you remove polyps that could develop into cancer, you can reduce cancer incidence, just like you can reduce breast cancer by simply amputating all breasts preemptively. That doesn’t mean that the procedure of the amputating all breasts preemptively has a positive effect on lifespan even when it reduces your breast cancer incidence.
The procedural mortality from colonoscopy is well-characterized at roughly 0-1 deaths per 10,000 (NordICC saw zero in 12,574).
The per-protocol CRC mortality reduction was 15 [7-22] per 10,000 absolute. So even at the low end of the CI, known procedural harms eat at most ~15% of the benefit.
For the net to come out neutral or negative, you’d need an unidentified mechanism of death an order of magnitude larger than every characterized harm. Theoretically unfalsified, yes, but not actually how one should reason about established procedures.
Take for example appendectomy, there’s no powered ACM RCT of appendectomy vs no treatment either, and there never will be (although appendectomy vs antibiotics is very much on the table, other issue!).
The ‘cause-specific reduction doesn’t prove ACM benefit’ idea is usually fine imo, and applies in cases like PSA screening or mammography in 40-year-olds, where the cause-specific benefit is small, overdiagnosis is large, and downstream treatments carry meaningful mortality. Colonoscopy isn’t structurally that case: the cause-specific benefit is large in relative terms, polypectomy harms are well-mapped and small, and removing adenomas isn’t analogous to treating overdiagnosed prostate cancer with prostatectomy.
Pattern matching from one to the other doesn’t work. For similar reasons, the breast analogy doesn’t hold so well.
Medicine did use to do appendectomy routinely in people without specific problems with the appendix if there was an operation in that general area and it’s generally believed that this was bad so clinical guidelines changed.
I have no reason to believe that’s the case. Just because you well-mapped the area under the streetlamp in search for your key does not mean that you have generally well-mapped the locations where your key might be. The harms that are well mapped are those that show serious clinical signs shortly after the intervention. If you for example take depression due to major head trauma you can only see half of the cases after three months. Delayed effects are a thing. If a treatment increases the lowest nightly heartrate by 5 points that wouldn’t show up as a serious clinical sign in standard medical studies but it would still be a pretty significant side effect that increases mortality.
We do have fairly large amount of lower back pain that’s unexplained by standard medicine. This is because we have a relatively poor understanding and fascia and a few other mechanisms. Osteopaths have a good understand that scars in general can create problems for bodily organization. Besides the scars you probably also have more inflammation and trauma where the effects are poorly mapped.
If you take appendectomy, the effects of the scar that are still perceivable decades afterwards in bodily organization with regards to tension, are not well-mapped. I don’t have any hands-on experience with effects of polypectomy, but I think it’s plausible to have similar issues.