| Date | Event | Description |
|---|---|---|
| 2 June 2010 | New citation required but conclusions have not changed | The review is being republished to correct the citation version. |
| 28 October 2009 | New search has been performed | Updated. |
| 30 October 2008 | Amended | Converted to new review format. |
| 17 August 2006 | Amended | New studies sought but none found. |
| 18 June 2006 | Amended | Minor update. |
| 7 January 2005 | Amended | New studies found and included or excluded. |
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