TABLE 1
FROM:
Guidelines for the management of patients who are taking oral anticoagulants and who require dental surgery
Derek Richards
BACK TO ARTICLETable 1. Classification of evidence levels and grades of recommendations
| Evidence level | Required standard |
| Ia | Evidence obtained from meta-analysis of RCT |
| Ib | Evidence obtained from at least one RCT |
| IIa | Evidence obtained from at least one well-designed controlled study without randomisation |
| IIb | Evidence obtained from at least one other type of well-designed quasi-experimental study* |
| III | Evidence obtained from well-designed nonexperimental descriptive studies, eg, comparative studies, correlation studies and case studies |
| IV | Evidence obtained from expert committee reports or opinions and/ or clinical experiences of respected authorities |
| Grades of recommendations | |
| A | Requires at least one RCT as part of a body of literature of overall good quality and consistency addressing specific recommendation (evidence levels Ia, Ib) |
| B | Requires availability of well-conducted clinical studies but no RCT on topic of recommendation (evidence levels IIa, IIb, III) |
| C | Requires evidence obtained from expert committee reports or opinions and/ or clinical experiences of respected authorities. Indicates an absence of directly applicable clinical studies of good quality (evidence level IV) |
*A situation in which implementation of an intervention is beyond the control of the investigators, but an opportunity exists to evaluate its effect.
RCT, Randomised controlled trial.