| Quality of evidence |
| High |
Randomized controlled trials without important limitations or meta-analysis or double-upgraded observational studies. Further research is very unlikely to change our confidence in the estimate of effect |
A |
| Moderate |
Downgraded randomized controlled trials; upgraded observational studies. Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate |
B |
| Low |
Double-downgraded randomized controlled trials; observational studies; case series/case reports. Further research is very likely to have an important impact on our confidence in the estimate of effect and may change the estimate |
C |
| Very low |
Triple-downgraded randomized controlled trials; downgraded observational studies; expert opinion. Further research is most likely to have an important impact on our confidence in the estimate of effect and change the estimate probably. Any estimate of effect is uncertain |
D |
| Strength of recommendation |
| Strong recommendation |
Good evidence to support a recommendation for use or against use. Factors influencing the strength of the recommendation include the quality of the evidence, presumed patient-important outcomes, and cost |
I |
| Weaker recommendation |
Moderate evidence to support a recommendation for use or against use. Variability in preferences and values or greater uncertainty: more likely a weak recommendation is warranted. Recommendation is made with less certainty; higher cost or resource consumption |
II |
| Ungraded recommendation |
Poor evidence to support a recommendation. The pros and cons of taking interventions are quite unclear. Failed to identify target population |
UG |
