| Date | Event | Description |
|---|---|---|
| 16 January 2012 | New citation required but conclusions have not changed | No change to conclusions. Text updated throughout |
| 17 December 2011 | New search has been performed | Searches updated to February 2012. No RCTs identified but two non‐randomised studies added to the Discussion. Methods revised to reflect updated Cochrane 'Risk of bias' methodology |
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