| Date | Event | Description |
|---|---|---|
| 16 September 2014 | New search has been performed | Searches updated 16th September 2014 |
| 16 September 2014 | New citation required but conclusions have not changed | Three new studies included; conclusions remain the same |
| 1 November 2010 | New search has been performed | Searches updated 1st November 2009; no new trials identified |
| 12 August 2009 | Amended | Copyedits made at editorial base |
| 23 September 2008 | Amended | Converted to new review format |
| 26 September 2007 | New search has been performed | Searches updated 27th July 2007; no new trials identified |
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.