Date	Event	Description
12 June 2008	Amended	Converted to new review format.
18 April 2004	New search has been performed	We identified 52 new trials and increased the number of included patients from 8525 to 11,737 (38%). Confidence intervals became narrower, more clinical conditions had been investigated by three trials or more.
18 April 2004	New citation required and conclusions have changed	We updated the review on issue 3 2004 of The Cochrane Library. The degree of heterogeneity between trials with continuous outcomes was more pronounced in this update, but the main findings were( identical to the previous version of the review (Hróbjartsson 2003a).