Supplementary Table 2.

Methodological index for nonrandomized studies bias assessment

Author	Clearly stated aim	Inclusion of consecutive patients	Prospective collection of data	Endpoints appropriate to the aim of study	Unbiased assessment of the study endpoints	Prospective calculation of study sample	Total MINORS score	Oxford level of evidence
Crisp, 1976[6]	0	0	0	1	1	0	2	4
Abrams, 1981[7]	0	0	2	2	2	0	6	4
Kaplan, 1996[8]	2	0	0	2	2	0	6	4
Kaplan, 1997[9]	2	0	0	2	2	0	6	4
Nitti, 2002[3]	2	2	2	2	2	0	10	2B
Wang, 2003[10]	2	2	2	2	2	0	10	2B
Toh, 2006[11]	2	0	0	2	2	0	6	4
Karami, 2011[12]	2	0	2	2	2	0	8	2B
Jamzadeh, 2014[13]	2	0	0	2	2	0	6	4
Jeong, 2014[14]	2	0	0	2	2	0	6	4
MINORS Scale interpretation
Interpretation of individual factors			Score of individual factors
Not reported			0
Reported but inadequate			1
Reported and adequate			2

MINORS >50% is considered high-quality study. MINORS=Methodological index for nonrandomized studies