“…Of these, 39 articles were eligible to be included in the systematic review. In addition, 4 articles were added from the references (Fardal, 2006;Kim, Lee, Chang, & Um, 2014;Konig, Plagmann, Langenfeld, & Kocher, 2001;Wilson et al, 1984); hence, a total number of 31 cohort studies (Agrawal, Jain, Jain, Agarwal, & Dubey, 2015;Cardaropoli & Gaveglio, 2012;de Carvalho et al, 2010;Checchi, Pelliccioni, Gatto, & Kelescian, 1994;Delatola, Adonogianaki, & Ioannidou, 2014;Demetriou, Tsami-Pandi, & Parashis, 1995;Demirel & Efeodlu, 1995;Famili & Short, 2010;Fardal, Johannessen, & Linden, 2003;Frisch, Ziebolz, Vach, & Ratka-Kruger, 2014;Galgut, 1991;Hu, Lin, Ho, & Chou, 2017;Kakudate, Morita, & Kawanami, 2008;Kim et al, 2014;Konig et al, 2001;Mendoza, Newcomb, & Nixon, 1991;Mendoza et al, 1991;Miyamoto, Kumagai, Jones, Dyke, & Nunn, 2006;Nicholls, 2006;Novaes & Novaes, 2001;Novaes et al, 1999;Novaes, Novaes, Moraes, Campos, & Grisi, 1996;Ojima, Hanioka, & Shizukuishi, 2001;Ojima et al, 2005 Wilson et al, 1984;Wilson, Hale, & Temple, 1993;Zeza et al, 2017), 4 cross-sectional studies (Fenol & Mathew, 2010;Gokulanathan, Balan, Aravind, & Thangavelu, 2014;Monje, Wang, & Nart, ...…”