> Number Needed to Treat (NNT) seems like a great idea. Will learn more. Thanks.

No problem, NNT and NNH are the most important measures we look at when deciding on interventions on a population level and easily understandable. "https://thennt.com" is a high quality resource intended for physicians but is fairly accessible to an educated reader and covers many common interventions one may face.

A lot of proposals have sounded great during my medical practice until the numbers come back with a NNT of 100,000 and NNH of 1000.

> Further, the more I read about cholesterol, the more confused I get. It seems to be a topic in a state of flux.

We used to have "LDL target < 2" when I was in training but my understanding is the general consensus amongst experts (and some recent evidence, but not enough to make a general recommendation) points to a stochastic relationship rather than a deterministic one/specific threshold with continued benefit scaling to 0 (found looking at hunter-gatherer indigenous populations).

> I think statins make sense for most patients. A cardiologist friend says everyone in their practice start statins preventatively by age 40 (?).

This is beyond my scope of practice (i.e. don't take this as medical advice) but anecdotally I also recently asked a cardiologist I greatly respect about a family member and his response was similar to what you were told, he started statins himself in his late 30s as male with "normal" cholesterol and no risk factors although the evidence is not yet there to support such liberal use and the guidelines don't recommend this (yet).

Beyond cholesterol reduction statins coincidentally also have plaque stabilizing effects that reduce the risk of MACE.

Given that there is next to zero harm with statin therapy and they're cheap, it seems like a reasonable intervention en masse in my non-domain expert opinion. The diabetes risk was overstated in earlier literature but we have better data now that their use is so widespread, myopathy is a self-limiting nothingburger that goes away when you stop/switch agents.

Personally, I'm planning start a statin soon as well regardless of my LDL levels (typical disclaimer of this is not evidence-based and a personal decision, discuss with your physician etc).

> And they'd know best, right?

Either endocrinology or cardiology would be good experts to ask as they live in this world. I would/did trust a cardiologist when I needed expert opinion on this personally.

> The risk of cherry picking examples is they'd distract from my thesis.

I mostly wanted to address the LDL as that has a strong body of evidence behind it.

The issue with your thesis otherwise is that most tests have no relevance without appropriate clinical context and if they won't change management what's the point?

Consider radiology which is the land of meaningless incidentals, the issue we often face is "oh great, there's an incidental adrenal adenoma on this appendicitis scan that's probably nothing but could theoretically be an adrenal cancer what the hell do we do now?".

A single baseline would often be nice in the sense of if a patient did develop a non-adrenal cancer I could look back and say "oh this was there before, it's not metastatic" but there isn't enough evidence to support this statement considering the potentially life-threatening harms from over-investigating benign findings with biopsies/surgery. This has been the main criticism of whole-body screening MRI but the literature is just starting to come out.