About

How assessments are made

Evidence comes only from PubMed, Europe PMC, ClinicalTrials.gov, preprint servers (marked as preliminary) and regulatory documents. Press releases, marketing, investor material and news coverage are never used as evidence.

For each study the collection keeps two things apart: the facts reported in the paper, such as the number of participants or the size of an effect, and our judgments about them, such as how closely the population matches the reference group or whether weight loss could explain the result. Judgments are versioned; earlier versions stay on record.

Study tiers describe a single study. Certainty ratings are different: they apply to a whole body of evidence for one outcome. This collection rates certainty on its own scale — well supported, supported, mixed, weak, or untested — using the same five domains a formal GRADE assessment uses: risk of bias, inconsistency, indirectness, imprecision, and reporting bias. Every rating shows its reasoning for all five.

Our scale is not GRADE, and we do not describe it as GRADE. Where someone else has published a formal GRADE rating for an outcome — a Cochrane review, a guideline panel — we import it and show it as theirs, with the citation. The two are always labeled so you can tell which you are reading.

One level is worth explaining. Untested does not mean the evidence is poor. It means the question has not been properly asked: no study in the body uses a design that could answer it, or the studies that could answer it did not report the result. That is a fact about the literature, and it is different from a weak answer. Not yet assessed is different again — it means we have not done the work, and says nothing about the evidence.

Claim statuses sit above outcome certainty and are the collection's own judgment across several outcomes. They are never certainty ratings.

A change in a biomarker such as CRP is never treated as a clinical benefit, and animal or mechanistic findings are never treated as evidence about people.