Table 1.

Risk of bias of the included randomised clinical trials (9-item Cochrane checklists for randomised trials

	Randomisation	Concealed randomization	Blinded patients	Blinded treaters	Blinded Assessors	Groups comparable	Loss to follow up	Intention to treat	Groups treated equaly
Connolly 1992 [29] 6/9	+	-	+	+	-	-	+	+	+
Coppin 2005 [5] 8/9	+	+	-	+	+	+	+	+	+
Garrison 2011 [17] 9/9	+	+	+	+	+	+	+	+	+
Hallegraeff 2012 [9] 9/9	+	+	+	+	+	+	+	+	+
Jansen 1997 [18] 9/9	+	+	+	+	+	+	+	+	+
Roffe 2002 [19] 8/9	+	+	+	+	-	+	+	+	+
Serrao 2001 [14] 3/9	+	-	-	-	-	-	+	-	+
Young 1993 [15] 1/9	-	-	?	?	?	?	-	?	+

Coppin 2005 [5], Garrison 2011 [17], Hallegraeff 2012 [9], Jansen 1997 [18] and Roffe 2002 [19] showed low risk of bias