| Date | Event | Description |
|---|---|---|
| 29 March 2011 | New citation required but conclusions have not changed | G Pfeffer included among authors |
| 29 March 2011 | New search has been performed | New searches to July 2011. Six new studies included and two previously included studies now excluded, resulting in 10 included studies. Incorporated revised 'Risk of bias' methods |
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