| Date | Event | Description |
|---|---|---|
| 20 October 2009 | New search has been performed | We revised search strategies and ran new searches. We limited the types of studies included to RCTs only. One study (Guarino 2006) has been added to the review; this had no substantial impact upon the review's conclusions. This updated review was first published on issue 1 2010 of The Cochrane Library. |
| 20 October 2008 | Amended | Converted to new review format. |
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