| Date | Event | Description |
|---|---|---|
| 4 August 2010 | New citation required but conclusions have not changed | New team of authors. |
| 4 June 2010 | New search has been performed | Searches updated to September 2009. No studies identified for inclusion. Additional studies considered in the Discussion. |
| 9 July 2008 | Amended | Converted to new review format. |
| 1 June 2006 | New citation required and conclusions have changed | Substantive amendment |
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