| GRADE evidence | |
|---|---|
| I | Randomized, controlled trials |
| II-1 | Controlled trials without randomization |
| II-2 | Cohort or case-control analytic studies |
| II-3 | Multiple time series, dramatic uncontrolled experiments |
| III | Opinions of respected authorities, descriptive epidemiology |
Grading of Recommendations Assessment Development and Evaluation (GRADE) system used in the Clinical Practice Guidelines for Liver Transplantation in Saudi Arabia