“…Twelve studies were published in journals (Campbell et al, 2008;Bajaj et al, 2009;Choi et al, 2011;Goel et al, 2012;van Vlerken et al, 2012;de Vos et al, 2013;Kwon et al, 2014;Merli et al, 2014;Min et al, 2014;Miura et al, 2014;O'Leary et al, 2014;Ratelle et al, 2014) and 5 studies were reported as conference abstracts (Northup et al, 2008;Bulsiewicz et al, 2009;Aditi et al, 2012;Terg et al, 2012;Mandorfer et al, 2014). We included 8 retrospective cohort studies, 6 case-control studies, and 3 prospective cohort studies.…”