Table 3.

Quality assessment of the studies according to the Quality in Prognosis Studies (QUIPS) criteria (Hayden et a.l, 2013), illustrated in Figure 2.

Author	Year	Study participation	Study attrition	Prognostic factor measurement	Outcome measurement	Study confounding	Statistical analysis and reporting
Beenken S. et al.	1994	high	moderate	moderate	low	moderate	moderate
Beenken S. et al.	1999	high	moderate	moderate	low	moderate	moderate
Chang P. et al.	2013	moderate	moderate	high	moderate	moderate	low
Fernandez-Valle Á. et al. (A)	2016	low	low	low	low	low	low
Fernández-Valle Á. et al. (B)	2016	moderate	low	low	moderate	moderate	low
Foy JP. et al.	2015	low	low	low	low	moderate	low
Kawaguchi H. et al.	2008	low	low	low	moderate	moderate	low
Lee JJ. et al.	2000	low	low	low	low	moderate	low
Lin CY. et al.	2010	low	moderate	moderate	moderate	high	low
Mao L. et al.	1996	low	low	low	moderate	low	low
Massarelli E. et al.	2005	low	low	moderate	low	low	low
Nagao T. et al.	2017	moderate	low	moderate	moderate	moderate	moderate
Nayak S. et al.	2015	low	moderate	moderate	moderate	moderate	low
Rai B. et al.	2010	moderate	moderate	moderate	moderate	moderate	moderate
Saintigny P. et al.	2009	low	low	low	low	moderate	low
Saintigny P. et al.	2011	low	low	low	low	low	low
Saintigny P. et al.	2018	low	low	low	low	moderate	low
Sakata J. et al.	2017	low	low	low	low	low	low
Tanić N. et al.	2009	low	low	low	low	moderate	low
Uehara M. et al.	2010	low	moderate	moderate	moderate	moderate	low
Visioli F.	2012	low	low	moderate	moderate	moderate	low
Wan XS.	1999	low	moderate	moderate	moderate	moderate	moderate
Xiao W	2012	low	moderate	low	moderate	moderate	low
Yang CZ	2014	moderate	moderate	low	moderate	moderate	low
Yang Y	2013	moderate	moderate	moderate	low	moderate	low