Date	Event	Description
11 June 2018	New citation required but conclusions have not changed	Search updated. Five new studies included, three new ongoing studies identified, seven additional studies excluded and two studies classed as awaiting classification. Text amended to reflect current Cochrane policy. Conclusions changed.
11 June 2018	New search has been performed	Search updated. Five new studies included, three new ongoing studies identified, seven additional studies excluded, and two studies classed as awaiting classification.