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.
| Levels of evidence | Definition |
|---|---|
| Evidence A | Data derived from multiple RCTs or meta-analyses. |
| Evidence B | Data derived from a single RCT or large non-randomized studies. |
| Evidence C | Consensus of opinion of the experts and/or small studies, retrospective studies, registries. |
RCT = randomized controlled trial.
