| Date | Event | Description |
|---|---|---|
| 2 April 2013 | Amended | Edits to contact details |
| 10 September 2012 | New search has been performed | Review has been updated |
| 10 September 2012 | New citation required but conclusions have not changed | New authors, now has 45 studies. |
| 16 June 2011 | Amended | Minor edits |
| 18 February 2009 | Amended | Minor edits |
| 12 November 2008 | Amended | Minor changes |
| 23 April 2008 | Amended | Converted to new review format. |
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