| Date | Event | Description |
|---|---|---|
| 26 September 2012 | New citation required but conclusions have not changed | Review updated. |
| 26 September 2012 | New search has been performed | Two studies identified from an updated search have been assessed for eligibility and both have been excluded. Methods have been updated. |
| 27 January 2012 | Amended | Search updated. Two trial reports added to Studies awaiting classification (Burwick 2011; Simcox 2009). |
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