Table 2.

Risk-of-bias summary

Study	Study design	Sequence generation (selection bias)	Allocation concealment (selection bias)	Blinding of outcome assessors for all outcomes	Blinding of participants and personnel (performance bias)	Incomplete outcome data (attrition bias)	Selective reporting (reporting bias)
Khoo et al, 2013	RCT	Low	Low	Low	High	Low	Low
Maio et al, 2010	RCT	Low	Low	Unclear	High	Low	Low
Esposito et al, 2009	RCT	Low	Unclear	Unclear	High	Low	Low
Kalka et al, 2013	RCT	Low	Unclear	Unclear	High	Low	Low
Lamina et al, 2009	RCT	Low	Unclear	Unclear	High	Low	Low
Begot et al, 2015	RCT	Low	Unclear	Unclear	High	Low	Low
Maresca et al, 2013	RCT	High	Unclear	Unclear	High	Low	Low
Kalka et al, 2015	CT	High	High	Unclear	High	Low	Low
Kalka et al, 2016	CT	High	High	Unclear	High	Low	Low
La Vignera et al, 2011	CT	High	High	Unclear	High	Low	Low

CT = controlled trial; RCT = randomized controlled trial.