Study Year of
publication 		Reasons for exclusion
Mettraux et al. [6] 2015 Retrospective study
Heitz-Mayfield et al. [10] 2011 Short follow-up
Ji et al. [11] 2014 Short follow-up
McKenna et al. [12] 2013 Short follow-up
Mussano et al. [13] 2013 Short follow-up
Lerario et al. [14] 2016 Retrospective study
Parma-Benfenati et al. [15] 2013 Review
Renvert et al. [16] 2011 Same sample as Persson et al. [26]
Sahm et al. [17] 2011 Same sample as John et al. [24]
Schär et al. [18] 2013 Same sample as Bassetti et al. [21]
Sreenivasan et al. [19] 2011 Unclear and incomplete data