Classification scheme for the strength of evidence
| Strength of Evidence | Criteria Used |
|---|---|
| Strong | Studies with broad generalizability to most patients suspected of having the disease; include prospective, blinded comparison of a diagnostic test with a well-defined final diagnosis in an unbiased sample when assessing diagnostic accuracy or blinded randomized control trials when assessing therapeutic impact or patient outcomes; also included are well-designed meta-analyses |
| Moderate | Prospective or retrospective studies with narrower spectrum of generalizability, with only a few flaws that are well-described so that their impact can be assessed but still include a blinded study of diagnostic accuracy on an unbiased sample (well-designed cohort or case-control studies) and randomized trials for therapeutic effects or patient outcomes |
| Limited | Diagnostic accuracy studies with several flaws in research methods, small sample sizes, incomplete reporting, or nonrandomized comparisons for therapeutic impact or patient outcomes |
| Insufficient | Studies with multiple flaws in research methods, case series, descriptive studies, or expert opinions without substantiating data |