Date	Event	Description
30 March 2012	New citation required but conclusions have not changed	We have included study flow, risk of bias and summary of finding tables in this updated review.
30 March 2012	New search has been performed	We previously updated the review Bennett 2007) until October 2009. In this updated version we reran the searches until 6 October 2011. No new trials have been found.
5 November 2009	New search has been performed	We updated the search to October 23rd 2009. No new studies were found. We moved one ongoing study (Francis 2002) to the excluded studies section because the study did not continue and no data was supplied. We have removed one ongoing study from the review as it did not take place (Hink 2005).
11 March 2008	Amended	Converted to new review format.