Table 1.

Summary of Study Design of Included Studies

Study design	Reference
Randomized controlled trial	Theophilus et al. (2011), Chunder et al. (2012), Williams et al. (2013)
Prospective cohort study	Sato et al. (2011), Short et al. (2011), Anaya et al. (2012), Pathak et al. (2014), Opoien et al. (2007), Watanabe et al. (2008), Harbarth et al. (2008), Korinek et al. (2005), Uchino et al. (2013), Howard et al. (2010), Neuman et al. (2014), Valentini et al. (2008), Hubner et al. (2011), Ridgeway et al. (2005), Ogihara et al. (2015), Nagano et al. (2014), Khoshbin et al. (2014), Utsumi et al. (2010)
Retrospective cohort study	Nanashima et al. (2014), Kremers et al. (2015), Naranje et al. (2015), Winocour et al. (2015), Nguyen et al. (2012), Showalter et al. (2013), Han et al. (2014), Li et al. (2013), Biscione et al. (2007), Boltz et al. (2011), Davis et al. (2013), Sergeant et al. (2008), Kiran et al. (2010), Drosdeck et al. (2013), Kurmann et al. (2011), Maoz et al. (2015), Mraovic et al. (2011), Zhan et al. (2014), Ata et al. (2010), Suzuki et al. (2010), Haridas et al. (2008), Elola-Olaso et al. (2012), Mahdi et al. (2014), Hagihara et al. (2012), Suehiro et al. (2008), Colman et al. (2013), Nakahira et al. (2013), Bures et al. (2014), Astagneau et al. (2009), Namba et al. (2013), Sadamori et al. (2013), Ogihara et al. (2009), Smith et al. (2012), Alavi et al. (2010), Miki et al. (2006), Lake et al. (2013), Hellinger et al. (2009), Lin et al. (2014), Tran et al. (2015), Elfenbein et al. (2014), Lee et al. (2011), Ma et al. (2012), Campbell et al. (2008), George et al. (2011), Aimaq et al. (2011), Wick et al. (2009), Freire et al. (2013), Fukuda et al. (2013), Herruzo et al. (2013), Cordero-Ampuero et al. (2010), Willis-Owen et al. (2010), Stremitzer et al. (2010), Kohut et al. (2015), Skramm et al. (2012)
Retrospective case control study	Kourbatova et al. (2005), Peersman et al. (2006), Lopez-Ben et al. (2014)
Systematic review and Meta-analysis	Korol et al. (2013), Gibbons et al. (2011) Mavros et al. (2011)