Table 3. Risk of bias of included trials.

StudyRef	Design	Publication type	Withdrawals and dropouts	Quality score	Quality criteria not fulfilled
Salama et al.29	RCT	Article	No	10	i, l, m, n
Lyra et al.14	RCT	Article	No	10	i, l, m, n
Amer et al.16	Case-control	Article	No	9	a, i, l, m, n
Peng et al.15	Case-control	Article	No	9	a, i, l, m, n
El-Ansary et al.30	Case-control	Article	No	9	a, i, l, m, n
Mohamadnejad et al.32	RCT	Article	No	12	m, n
Liao et al.31	Case-control	Article	No	9	a, i, l, m, n
Xu et al.17	RCT	Article	No	12	m, n
Bai et al.34	Case-control	Article	No	9	a, i, l, m, n
Liu et al.33	RCT	Article	No	10	i, l, m, n
Salama et al.35	RCT	Article	No	10	i, l, m, n
Al Tayeb et al.36	Case-control	Article	No	9	a, i, l, m, n
Suk et al.38	RCT	Article	No	10	i, l, m, n
Mohamadnejad et al.37	RCT	Article	No	14	No*
Wu et al.39	RCT	Article	No	10	i, l, m, n

No*, the study got 14 “Yes” in the risk test.

Abbreviation: RCT, randomized controlled trial.