Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Approach applied to assign the final level of certainty in a causal relationship. Adapted from OHAT‐NTP (2019). HCT, human controlled trial; LoE, line of evidence; NCC, nested case–control; PC, prospective cohort study; RoB, risk of bias. aAs an example, a ‘high level of certainty’ means that, based on the available evidence, experts are 75%–100% certain that folate intake is positively and causally associated with the adverse health outcome of interest.
