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 [42]
| Strong | Consistent findings among multiple high-quality RCTs (two trials or more) |
| Moderate | Consistent findings among multiple weak- or moderate-quality RCTs (three trials or more) or with one high-quality RCT |
| Limited | One or two weak- or moderate-quality RCTs |
| Conflicting | Inconsistent findings among multiple RCTs |
| No evidence from trials | No RCTs |
