| Date | Event | Description |
|---|---|---|
| 15 February 2010 | New search has been performed | This review has been updated with a new search (August 2010) but no new relevant studies were found. 'Risk of bias' and 'Summary of findings' tables have been included. |
| 27 May 2008 | Amended | Converted to new review format. |
| 14 November 2007 | New citation required and conclusions have changed | Substantive amendment |
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