Table 4

Risk of bias of included prediction model studies

Study ID	Participants	predictors	Outcome	Sample size and missing data	Statistical analysis
Zhang et al (2015)40	L	L	L	H	H
Tolenaar et al (2014)8	L	L	L	H	H
Mehta et al (2002)7	L	L	L	U	U
Ghoreishi et al (2018)41	L	L	H	U	H
Centofanti et al (2006)42	L	L	L	U	H
Santini et al (2007)43	L	L	L	U	H
Rampoldi et al (2007)44	L	L	L	L	H
Leontyev et al (2016)45	L	L	L	U	H
Zhang et al (2019)46	L	L	L	H	H
Macrina et al (2010)47	L	L	L	H	H
Macrina et al (2009)48	L	L	L	H	H
Ge et al (2013)49	H	H	L	H	H
Yu et al (2016)50	L	L	L	H	H
Vrsalovic et al (2015)9	L	L	L	H	H

L, low risk; H, high risk; U, unclear risk.