| Date | Event | Description |
|---|---|---|
| 17 October 2011 | New search has been performed | Searches were updated. No new trials were included. Two new studies were excluded (Jee 2010; Singh 2010). An ongoing trial was updated (Sokala). |
| 9 March 2009 | New search has been performed | Updated searches; no completed RCTs were included. Added searches of clinical trials databases; listed one trial in progress. |
| 15 April 2008 | Amended | Converted to new review format. |
| 20 December 2006 | New citation required and conclusions have changed | Substantive amendment |
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