Table 8.7.a: Possible approach for summary assessments of the risk of bias for each important outcome (across domains) within and across studies

Risk of bias

Interpretation

Within a study

Across studies

Low risk of bias.

Plausible bias unlikely to seriously alter the results.

Low risk of bias for all key domains.

Most information is from studies at low risk of bias.

Unclear risk of bias.

Plausible bias that raises some doubt about the results.

Unclear risk of bias for one or more key domains.

Most information is from studies at low or unclear risk of bias.

High risk of bias.

Plausible bias that seriously weakens confidence in the results.

High risk of bias for one or more key domains.

The proportion of information from studies at high risk of bias is sufficient to affect the interpretation of results.