|
Grades of Evidence |
|
| A |
Systematic reviews of randomized controlled trials and/or randomized controlled trials. |
| B |
Systematic reviews of observational studies and/or high-quality observational studies including cohort and case-control studies. |
| C |
Case-series, case-reports and/or poor quality cohort and case-control studies. |
| D |
Expert opinion without explicit critical appraisal, or based on physiology, bench research or "first principles." |
Prousky and Seely Nutrition Journal 2005 4:3 doi:10.1186/1475-2891-4-3 |
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