Table 3

Decreasing and increasing the grade of evidence

Decrease grade if*Serious or very serious limitation to study quality
Important inconsistencies in results
Some or major uncertainty about directness of the evidence
Imprecise or sparse data (relatively few participants and/or events)
High probability of reporting bias
Increase grade ifMagnitude of the treatment effect is very large and consistent
Evidence of a large dose–response relation
All plausible confounders/biases would have decreased the magnitude of an apparent treatment effect