Table 3.

Risk of bias assessment.

Study	Random Sequence Generation	Allocation Concealment	Blinding of Participants/Personnel	Blinding Outcome Assessors	Incomplete Outcome Data	Selective Reporting	Other Bias
Alaghband-Rad and Hakimshooshtary (28)	?	?	?	?	-	-	-
Asbahr et al. (27)	?	?	-	-	+	+	+
Geller et al. (30)	?	?	?	?	+	+	+
Geller et al. (31)	+	?	?	?	-	+	-
Liebowitz et al. (29)	?	?	?	+	+	+	+
March and Friesen (32)	+	?	+	?	+	-	+
Neziroglu et al. (26)	?	?	-	?	+	+	+
POTS (4)	+	+	?	+	?	+	+
Riddle et al. (25)**	?	+	+	?	+	+	+
Riddle et al. (33)	?	?	+	+	+	+	+
Skarphedinsson et al. (18)	+	+	-	?	+	+	+
Storch et al. (24)	+	+	?	+	+	+	+

“+” is of low risk; “-”is of high risk; “?” is of unclear risk.