“…Sources of bias most commonly related to study attrition, specifically lack of details provided regarding reasons for loss to followup or differences in key characteristics between those included and those lost to follow-up. Nine studies (Avlund et al, 2000;Ayis, Bowling, Gooberman-Hill, & Ebrahim, 2007;Ayis et al, 2006;Eronen et al, 2013;Manty et al, 2009;Onder et al, 2003;Rantakokko et al, 2012;van den Brink et al, 2004;Weiss et al, 2012) (9/58, 16%) were rated as high risk of bias for the study attrition domain, and 33 studies (Abizanda et al, 2013;An & Lu, 2016;Auais et al, 2018Auais et al, , 2019Avlund, Damsgaard, & Osler, 2004;Avlund et al, 2002;Avlund, Lund, et al, 2004;Avlund, Pedersen, & Schroll, 2003;Carbone et al, 2013;Chen et al, 2012;Crimmins & Saito, 1993;Deshpande et al, 2014;Duan-Porter et al, 2019;Eggermont et al, 2014;Fried et al, 2000;Guralnik, Ferrucci, Balfour, Volpato, & Di Iorio, 2001;Koster et al, 2005;LaCroix et al, 1993;Lang et al, 2008;Lee et al, 2005;Leveille et al, 2001Leveille et al, , 2007Lindberg & Tilvis, 1998;Mänty et al, 2007;Nilsson et al, 2008Nilsson et al, , 2010Pine, Gurland, & Chren, 2000Rantakokko et al, 2016;<...>…”