| Date | Event | Description |
|---|---|---|
| 13 October 2011 | New search has been performed | Searches were updated; no new trials found. |
| 9 March 2009 | New search has been performed | Updated searches; added searches of clinical trials databases. No new trials were found. |
| 15 April 2008 | Amended | Converted to new review format. |
| 9 January 2007 | New citation required and conclusions have changed | Substantive amendment |
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