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Levels of Evidence
| I | Evidence obtained from high quality diagnostic studies, prospective studies, or randomized controlled trials |
| II | Evidence obtained from lesser-quality diagnostic studies, prospective studies, or, randomized controlled trials (eg, weaker diagnostic criteria and reference standards, improper randomization, no blinding, <80% follow-up) |
| III | Case controlled studies or retrospective studies |
| IV | Case series |
| V | Expert opinion |
