| Date | Event | Description |
|---|---|---|
| 7 February 2012 | Review declared as stable | Information added to Published notes about the updating of this review. |
| 27 May 2008 | Amended | Converted to new review format. |
| 31 July 2007 | New citation required and conclusions have changed | This review was updated in February 2007. We redid the search completely in June 2006. Ten new trials were located. Compared to the previous version of this review, the conclusions have not altered substantially. |
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.