Table 2.

Risk of bias and applicability concern of the prediction models for brachytherapy-induced rectal toxicity in patients with pelvic cancers

	Study (year)	ROB				Applicability			Overall
		Participants	Predictors	Outcome	Analysis	Participants	Predictors	Outcome	ROB	Applicability
Cervix	Perez et al. (1999)	?	?	?	+	–	–	+	+	+
	Barillot et al. (2000)	+	+	+	+	–	+	–	+	+
	Chen et al. (2000)	?	?	+	+	–	–	+	+	+
	Chen et al. (2004)	?	?	?	+	+	+	–	+	+
	Wang et al. (2004)	?	?	+	+	+	–	+	+	+
	Saibishkumar et al. (2006)	?	?	?	+	–	–	–	+	–
	Noda et al. (2007)	?	?	?	+	–	–	–	+	–
	Chen et al. (2009)	?	?	?	+	+	+	–	+	+
	Chen et al. (2010)	?	?	?	+	+	–	–	+	+
	Kang et al. (2010)	?	+	+	+	–	–	+	+	+
	Huang et al. (2013)	–	?	?	+	–	–	+	+	+
	Kim et al. (2013)	–	–	?	+	–	–	–	+	–
	Kim et al. (2015)	?	?	+	+	–	–	–	+	–
	Ujaimi et al. (2017)	?	?	?	+	–	–	–	+	–
	Zhen et al. (2017)*	+	?	+	N.A.	?	?	?	N.A.	?
	Chen et al. (2018)*	+	?	+	N.A.	–	+	–	N.A.	+
Prostate	Merrick et al. (2003)	–	?	?	+	+	+	+	+	+
	Bittner et al. (2008)	–	?	–	+	+	–	+	+	+
	Zelefsky et al. (2008)	?	?	?	+	–	–	–	+	–
	Shiraishi et al. (2011)	?	?	+	+	–	–	–	+	–
	Keyes et al. (2012)	–	?	+	+	–	+	–	+	+
	Buckstein et al. (2013)	–	?	+	+	–	–	–	+	–
	Price et al. (2013)	?	?	?	+	–	–	+	+	+
	Shiraishi et al. (2013)	?	?	+	+	–	–	+	+	+
	Kang et al. (2015)	?	?	+	+	–	+	–	+	+
	Katayama et al. (2016)	–	+	?	+	–	–	–	+	–
	Kragelj et al. (2017)	?	?	+	+	–	+	–	+	+
	Tanaka et al. (2018)	?	?	?	+	–	+	–	+	+
	Ling et al. (2019)	–	–	+	+	–	–	+	+	+
Rectum	Rijkmans et al. (2019)	+	–	+	+	+	–	+	+	+

ROB – risk of bias; N.A. – not applicable; * non-regression modeling technique was used, for which PROBAST could not be applied on all domains; + indicates low ROB/low concern regarding applicability; – indicates high ROB/high concern regarding applicability; ? indicates unclear ROB/unclear concern regarding applicability