Chart 2. Quality of evidence interpretation following the Grading of Recommendations Assessment, Development and Evaluation system.^a .

Quality of evidence	Implication	Example
High ⨁⨁⨁⨁	Further research is very unlikely to change our confidence in the estimate of effect; we are confident that we can expect a very similar effect in the population for which the recommendation is intended	Randomized trials without serious limitations Well-performed observational studies with very large effects
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 a major impact on our confidence in the estimate of 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 effect is very uncertain	Randomized trials with very serious limitations and inconsistent results Observational studies with serious limitations Unsystematic clinical observations (e.g., case series or case reports)

^aAdapted from the Brazilian National Ministry of Health. ³⁷