Table 1.

ROBINS-I Assessment of Non-randomized studies: D1, Bias due to confounding; D2, Bias in selection of participants into the study; D3, Bias in classification of interventions; D4, Bias due to deviations from intended interventions; D5, Bias due to missing data; D6, Dias in measurement of outcomes; D7, Bias in selection of the reported result; X, high; –, some concern; +, low.

	D1	D2	D3	D4	D5	D6	D7	Overall
Mariani et al. (8)	–	–	+	+	+	+	+	+
Ruiz et al. (9)	X	X	+	+	+	+	–	–
Tasci et al. (10)	–	–	–	+	+	+	+	–
Chang et al. (11)	X	–	+	+	+	+	+	–
Duan et al. (12)	–	–	–	+	+	–	+	–