Table 2. The risks of bias of the included trials.

Source	Sequence generation	Allocation concealment	Patients blinded	Health care providers blinded	Data collectors blinded	Outcome assessors blinded	Incomplete outcome data	Selective reporting	Other bias	Overall risk
De Oliveira, 2011 [32]	Low	Low	Low	Low	Low	Low	Low	Unclear	Low	High
Murphy, 2011a [34]	Low	Low	Low	Low	Low	Low	Unclear	Unclear	Low	High
Murphy, 2011b [33]	Low	Low	Low	Low	Low	Low	Unclear	Low	Unclear	High
Pauls, 2015 [31]	Low	Low	Low	Low	Low	Low	High	Unclear	High	High