| Date | Event | Description |
|---|---|---|
| 24 September 2010 | Amended | Contact details updated. |
| 4 July 2010 | Amended | Contact details updated. |
| 13 May 2009 | Amended | Contact details updated. |
| 28 May 2008 | Amended | Converted to new review format. |
| 15 January 2008 | New search has been performed | Review updated - studies sought but none found |
| 15 January 2008 | New citation required but conclusions have not changed | Further studies satisfying our inclusion criteria were sought in MEDLINE (via Ovid), EMBASE (via Ovid) and Cochrane CENTRAL to December 2007. No further studies were identified, so the conclusions of the review are unchanged |
| 30 December 1999 | New citation required and conclusions have changed | Substantive amendment |
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