Grading of the level of methodological quality of individual studies (EBRO)
| Level of evidence | Interventional studies | Diagnostic accuracy studies | Harm, side effects, aetiology, prognosis |
|---|---|---|---|
| A1 | Systematic review/meta-analysis of at least two independently conducted studies of A2 level | ||
| A2 | Randomised, double blind trial with good study quality and an adequate number of study participants | Index test compared to reference test (reference standard); cut-offs were defined a priori; independent interpretation of test results; an adequate number of consecutive patients were enrolled; all patients received both tests | Prospective cohort study of sufficient magnitude and follow-up, adequately controlled for ‘confounding’ and no selective follow-up |
| B | Clinical trial, but without all the features mentioned for level A2 (including case–control study, cohort study) | Index test compared to reference test, but without all the features mentioned for level A2 | Prospective cohort study, but without all the features mentioned for level A2 or retrospective cohort study or case–control study |
| C | Non-comparative studies | ||
| D | Expert opinion | ||