| Date | Event | Description |
|---|---|---|
| 7 December 2021 | New citation required and conclusions have changed | One study newly included (Mayet 2021). Relevant sections have been updated. |
| 30 November 2021 | New search has been performed | Electronic searches were updated. |
| 4 July 2011 | New search has been performed | Issue 8 2011: Updated searches yielded no new trials. |
| 28 October 2008 | New search has been performed | Issue 1, 2009: updated searches yielded no new trials. Discussion section updated with new references. |
| 21 August 2008 | Amended | Converted to new review format. |
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