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 if
  • Magnitude 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