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The GRADE System for Grading Quality of Evidence and Strength of Recommendations[2,5] |
| Quality of evidence for each outcome (high, moderate, or low) – based on the following criteria: |
| • Study design– grade of high or low assigned based on design (RCT = high, observational study = low) |
| • Study quality– Detailed study methods and execution. |
| 1) Limitations in quality can decrease grade one or two levels. |
| 2) Evidence of reporting bias can also decrease grade one level. |
| 3) Grade can be increased one level if all plausible confounders would have reduced the treatment effect. |
| • Consistency of results– The level of similarity of estimates of effects across studies. |
| 1) Important inconsistency can decrease grade one level. |
| • Directness of evidence– the extent to which the people, interventions, and outcome measures are similar to those of interest. |
| 1) Some or major uncertainty about directness lowers the grade one or two levels. |
| • Other considerations |
| 1) Magnitude of effect can increase the grade of evidence. Strong evidence of association (significant relative risk of >2 or <0.5 based on consistent evidence from 2 or more observational studies with no plausible confounders) increases the grade by one level. Very strong evidence of association (significant relative risk of >5 or <0.2 based on direct evidence with no major threats to validity) increases the grade by two levels. |
| 2) Evidence of a dose-response gradient increases the grade by one level. |
| 3) Imprecise or sparse data can lower the grade by one level. |
| Relative importance of outcomes – included outcomes should be critical or important (but not critical) to a decision |
| Overall quality of evidence – judged across outcomes based on the lowest quality of evidence for any of the critical outcomes |
| Balance of benefits and harms – classified as net benefits, trade-offs, uncertain trade-offs, or no net benefits based on the important health benefits and harms |
| Balance of net benefits and costs – are incremental health benefits worth the costs? |
| Strength of recommendation – the extent to which one can be confident that adherence to a recommendation will do more good than harm |
Treadwell et al. BMC Medical Research Methodology 2006 6:52 doi:10.1186/1471-2288-6-52 |