Table 2.

The quality of the evidence was based on the grading quality of the evidence and the strength of the recommendations in clinical practice guidelines [7]. RCTs = randomized controlled trials.

Rank	Explanation	Examples
High	Further research is very unlikely to change our confidence in the estimate of the effect	Randomized trials without serious limitations Well-performed observational studies with very large effects (or other qualifying factors)
Moderate	Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate	Randomized trials with serious limitations Well-performed observational studies yielding large effects
Low	Further research is very likely to have an important impact on our confidence in the estimate of the effect and is likely to change the estimate	Randomized trials with very serious limitations Observational studies without special strengths or important limitations
Very low	Any estimate of the effect is very uncertain	Randomized trials with very serious limitations and inconsistent results Observational studies with serious limitations Unsystematic clinical observations (i.e., case series or case reports)