| Date | Event | Description |
|---|---|---|
| 30 July 2008 | Amended | Converted to new review format. |
| 6 May 2008 | New citation required and conclusions have changed | Substantive amendment |
| 30 September 2007 | New search has been performed | Searches updated to August 2007. Description of two more non‐randomised studies and two case reports added. |
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