Table 1.

Newcastle-Ottawa Scale (NOS) score for included studies

Study	Year	Selection				Comparability		Outcome			Scale
		Exposed	Non-exposed	Ascertainment of exposure	Start without outcome present	Major factor	Addition factor	Outcome assessment	Follow-up length	Adequacy of outcome
Badalato	2012	⭐	⭐	⭐	⭐	⭐	⭐	⭐	⭐		8
De Berardinis	2011	⭐	⭐	⭐	⭐	⭐	⭐	⭐	⭐		8
Denzinger	2008	⭐	⭐	⭐	⭐	⭐	⭐	⭐	⭐		8
Hautmann	2009	⭐	⭐	⭐	⭐		⭐	⭐			7
Jager	2011	⭐	⭐	⭐	⭐	⭐	⭐	⭐	⭐	⭐	9
Li	2011	⭐	⭐	⭐	⭐	⭐	⭐	⭐	⭐		8
Patard	2001	⭐	⭐	⭐	⭐		⭐	⭐	⭐		7
Spaliviero	2014	⭐	⭐	⭐	⭐	⭐	⭐	⭐			7
Sun	2008	⭐	⭐	⭐	⭐	⭐	⭐	⭐	⭐		8
Thalmann	2004	⭐	⭐	⭐	⭐	⭐	⭐	⭐	⭐		8
Wong	2009	⭐	⭐	⭐	⭐	⭐		⭐	⭐		7