Table 1 RTI Items elected to assess risk of bias and precision of the included studies

Selection bias

Sample definition and selection

Are critical inclusion/ exclusion criteria clearly stated?

• Age range, gender, etc. described?

• Specific inclusion/exclusion criteria stated?

Precision

Sample definition and selection

Was the sample size sufficiently large to detect a significant difference between groups?

• Justification for selected sample size given?

• Were sample size calculations performed?

Performance bias

Interventions/exposure outcomes

What is the level of detail in describing the intervention?

• Type of intervention, timing and frequency described?

• Was the intervention identical for all participants?

Selection bias

Creation of treatment groups

Is the selection of the comparison group appropriate

• Is there a comparison/ control group?

• If so, are there fundamental differences between the groups on the basis of socio-demographic variables and the outcome variables at baseline?

• Do the controls represent the population from which the intervention group arose?

Information bias

Soundness of information

Are the outcomes assessed using reliable measures?

• Was the reliability of the outcome assessment tested?

• If not, is the measurement protocol likely to yield reliable/valid results with regards to

- sampling duration

- number of repetitions

- visual condition

- foot position

based on a systematic review of the literature [18]

Overall judgment

• Low risk of bias: Bias, if present, is unlikely to alter the results seriously

• Unclear risk of bias: Impossible to determine risk of bias (either missing or not described well enough)

• High risk of bias: Bias may alter the results seriously