Design and created by Guideline Central in participation with the Centers for Disease Control and Prevention.
Centers for Disease Control and Prevention
Publication Date: May 1, 2019
Page Last Updated: May 5, 2026
| Category of Recommendation | Evidence Type | ||
| 1 | Applies to all persons; most patients should receive the recommended course of action. | 1 | Randomized clinical trials or overwhelming evidence from observational studies. |
| 2 | Individual decision making needed; different choices will be appropriate for different patients. Clinicians help patients arrive at a decision consistent with patient values and preferences and specific clinical situations. | 2 | Randomized clinical trials with important limitations, or exceptionally strong evidence from observational studies. |
| 3 | Observational studies or randomized clinical trials with notable limitations. | ||
| 4 | Clinical experience and observations, observational studies with important limitations, or randomized clinical trials with several major limitations. | ||
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