Table 12.2.d: Further guidelines for factor 1 (of 5) in a GRADE assessment: Going from assessments of risk of bias to judgements about study limitations for main outcomes
Risk of bias |
Across studies |
Interpretation |
Considerations |
GRADE assessment of study limitations |
Low risk of bias. |
Most information is from studies at low risk of bias. |
Plausible bias unlikely to seriously alter the results. |
No apparent limitations. |
No serious limitations, do not downgrade. |
Unclear risk of bias. |
Most information is from studies at low or unclear risk of bias. |
Plausible bias that raises some doubt about the results. |
Potential limitations are unlikely to lower confidence in the estimate of effect. |
No serious limitations, do not downgrade. |
Potential limitations are likely to lower confidence in the estimate of effect. |
Serious limitations, downgrade one level. |
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High risk of bias. |
The proportion of information from studies at high risk of bias is sufficient to affect the interpretation of results. |
Plausible bias that seriously weakens confidence in the results. |
Crucial limitation for one criterion, or some limitations for multiple criteria, sufficient to lower confidence in the estimate of effect. |
Serious limitations, downgrade one level. |
Crucial limitation for one or more criteria sufficient to substantially lower confidence in the estimate of effect. |
Very serious limitations, downgrade two levels. |