Table 3.

Risk of bias assessment adapted from Hayden et al

	Risk of Bias
Author	Participation	Attrition	Prognostic Factors	Outcome	Confounding	Analysis	Total Score
Attur 2011 [18]	Low	Low	Low	Low	Moderate	Low	Low
Bae 2010 [19]	Moderate	N/A	Low	Low	Moderate	Low	Low
Berry 2010a [20]	Moderate	Moderate	Low	Low	Moderate	Moderate	Low
Berry 2010b [21]	Low	Low	Low	Low	Moderate	Low	Low
Blumnenfeld 2013 [22]	Low	Moderate	Moderate	Moderate	Moderate	Moderate	Low
Cruz-Almeida 2013 [23]	Moderate	N/A	Low	Low	Moderate	Low	Low
Doss 2007 [24]	Moderate	N/A	Low	Moderate	Moderate	Low	Low
Egsgaard 2015 [25]	Moderate	N/A	Low	Low	High	Low	High
Fernández-Tajes 2014 [26]	Moderate	N/A	Low	Moderate	Moderate	Moderate	Low
Holla 2013 [27]	Moderate	Low	Low	Low	Low	Low	Low
Jenkins 2015 [28]	High	N/A	Moderate	Moderate	High	Moderate	High
Kerkhof 2008 [29]	Low	Low	Low	Low	Moderate	Low	Low
Kinds 2013 [9]	Moderate	Low	Low	Low	Moderate	Moderate	Low
King 2013 [30]	High	N/A	High	Low	High	Low	High
Knoop 2011 [7]	Low	N/A	Low	Low	Low	Moderate	Low
Murphy 2011 [31]	Moderate	N/A	Low	Moderate	Moderate	Low	Low
Otterness 2000 [32]	Moderate	N/A	Low	Moderate	Moderate	Moderate	Low
Pereira 2013 [33]	Low	N/A	Moderate	Low	Moderate	Low	Low
Roemer 2012 [34]	Low	N/A	Low	Low	Moderate	Moderate	Low
Sowers 2002 [35]	Moderate	Low	Low	Low	Moderate	Moderate	Low
Van der Esch 2015 [36]	Low	N/A	Low	Low	Moderate	Low	Low
Van spil 2012 [37]	Moderate	N/A	Low	Low	Moderate	Low	Low
Waarsing 2015 [8]	Low	N/A	Low	Low	Low	Low	Low
Iijima 2015 [38]	Moderate	N/A	Low	Low	High	Low	High
Kittelson 2015 [40]	Low	N/A	Low	Low	Low	Low	Low

N/A not applicable, the specific area of assessment was not applicable to the study