Table 2. Study characteristics related to the risk of bias.

Author/year	Randomization* (done/adequately described)	Allocation concealment* (done/adequately described)	Blinding# (done/adequately described)	Outcome assessment blinding* (done/adequately described)	Loss to follow-up described*	ITT analysis*	Selective reporting*
Clemensten/1998	Unclear	Unclear	No/clear	Yes/clear	Yes	Unclear	No
Caglayan/2008	Yes/clear	Unclear	No/clear	Yes/clear	Yes	Unclear	No
Porntepkasemson/2012	Yes/clear	Unclear	No/clear	Unclear	Yes	Unclear	No
Rahman/2015	Yes/clear	Unclear	No/clear	Yes/clear	Yes	Yes/clear	No

*, items indicating low risk of bias are shaded in green; ^#, items indicating high risk of bias are shaded in red. ITT, intention to treat.