| Study | Unit of randomisation | Unit of analysis |
| Baum 1987 | participants | ulcer |
| La Grenade 1993 | ulcer | ulcer |
| McMahon 2010 | participants | ulcer |
| Serjeant 1977 | participants | ulcer |
| Serjeant 1997 | participants | participants |
| Wethers 1994 | participants | participants |
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.