Level of evidence | Minimum quality* and quantity | Consistency | Strength of message |
---|---|---|---|
Strong | 3 High (H) | 3H agree; if 3+studies, 3/4 of the M and H agree | Recommendations |
Moderate | 2H or 2H and 1Medium (M) | 2H agree or 2M and 1H agree; if 3+, >2/3 of the M and H agree | Practice considerations |
Limited | 1H or 2M or 1M and 1H | 2 (M and/or H) agree; if 2+, >1/2 of the M and H agree | Not enough evidence to make recommendations or practice considerations |
Mixed | 2 | Findings are contradictory | |
Insufficient | Medium-quality studies that do not meet the above criteria |
*High is >85% in quality assessment; medium is 50–85% in quality assessment.