Table 1.

Grading of Recommendations Assessment, Development and Evaluation (GRADE) system [24] for rating quality of evidence and strength of recommendation

Factor	Description
Evidence:
High quality	Considerable confidence of the estimate of effect. Further research is very unlikely to change our confidence in the estimated effect.
Moderate quality	Confidence that the estimate is close to the truth. Further research is likely to have an important impact on our confidence in the estimate effect and may change the estimate.
Low quality	Limited confidence in the effect. Further research is likely to have an important impact on our confidence in the estimate effect and is likely to change the estimate.
Very low quality	Little confidence in the effect estimate. Any change of effect is uncertain.
Recommendation:
Strong: 'We recommend...'	A strong recommendation indicates that most well informed people will make the same choice
Weak: 'We suggest...'	A weak recommendation indicates that the majority of well informed people will make the same choice but a substantial minority will not
Uncertain: 'We cannot recommend...'	No specific recommendation for or against

Factors influencing the strength of the recommendation include evidence quality, risk/benefit aspects of presumed patient-important outcomes, costs and uncertainty concerning values and preferences.