| Date | Event | Description |
|---|---|---|
| 12 April 2012 | New search has been performed | Searches conducted. One new study was identified (Oliveira 2009) but our conclusions remain unchanged. Additional details were added to the Methods and the 'Risk of bias' tables. |
| 26 August 2011 | New citation required but conclusions have not changed | A new author joined the team to update this review. |
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