Table 4.

Summary of risk of bias for included studies

Studies	Study participation	Study attrition	Prognostic factor Measurement	Outcome Measurement	Statistical Analysis and Reporting
Bahali et al. [44]	Moderate	n/a	Low	Moderate	Low
Berg and McGuire [45]	High	n/a	Moderate	High	Low
Bernstein and Garfinkel [46]	Moderate	n/a	Low	Moderate	Low
Carless et al. [47]	Low	n/a	Low	Low	Low
Hansen et al. [48]	Low	n/a	Low	Low	Low
Heyne et al. [27]	Low	Moderate	Low	Low	Low
Last and Strauss [49]	Low	n/a	Low	Moderate	Low
Ozcan et al. [50]	Moderate	n/a	Low	Moderate	Low