Table 1.

GRADE quality of evidence^(11-16)

High (A)	Consistent, with evidence in randomized controlled trials or meta-analyses, without considerable limitations or with exceptionally strong evidence from observational studies. Further research is very unlikely to change the confidence in the estimate of effect.
Moderate (B)	Evidence from randomized controlled trials with considerable limitations (inconsistent results, methodological flaws, imprecision, indirect results). Further research is likely to have an impact on the confidence in the estimate of the effect and might change the estimate.
Low (C)	Evidence of at least one important result in observational studies, case series or randomized controlled trials with serious flaws or indirect evidence. Further research is very likely to have an impact on the confidence in the estimate of the effect and is likely to change the estimate.
Very low (C)	Any estimate of the effect is very uncertain.