Table 1.

Assessment of study quality using modified REMARK recommendations^a

Study quality question/Item	Marquardt et al., 2005 [26]	Montaner et al., 2006 [28]	Song et al., 2010 [29]	Winbeck et al., 2002 [27]	Rajeshwar et al., 2012 [21]
1. Was the study prospective?	Yes	Yes	Yes	Yes	Yes
2. Was the evaluation of prognostic marker blinded to patient outcome?	Yes	Yes	Yes	Unclear	Yes
3. Was there a defined time period during which patients were enrolled?	No	No	Yes	No	Yes
4. Were there precisely defined clinical outcomes at the beginning of the study?	Yes	Yes	Yes	Yes	Yes
5. Did the study provide a rational for sample size?	No	No	No	No	No
6. Did the study provide a list of candidate variables?	N/Ab	N/Ab	N/Ab	Yes	Yes
7. Were the methods for measuring the prognostic marker adequately described and referenced?	Yes	Yes	Yes	Yes	Yes
8. Were patients unselected/unbiased?	Yes	Yes	Yes	Yes	Yes

^aAdapted from McShane et al.²² and Whiteley et al.²³

^bStudy did not use multivariate modeling.

N/A = not available.