Table 2. Quality assessment of included studies.

Study	Randomization	Allocation concealment	Blindness	Blindness scheme	ITT analysis	Jadad score
Gray DS	Yes, method unknown	unknown	double-blind	unknown	unknown	2
O'Kane M	Yes, method unknown	unknown	double-blind	unknown	no	2
Breum L	Yes, method unknown	unknown	double-blind	unknown	unknown	2
Connolly VM	Yes, method unknown	unknown	double-blind	unknown	no	2
Daubresse JC	Yes, method unknown	unknown	double-blind	unknown	unknown	2