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Agreement for the stratification of the levels of evidence.
| Level of Evidence | Type of Study | Solidity |
|---|---|---|
| A | Meta-analysis | Very strong |
| Systematic reviews. | Strong | |
| B | Randomized clinical trials. | Moderate |
| Cohort studies. Case-control studies. | ||
| C | Non-analytical or experimental studies | Low |
| D | Opinion of the committee of experts. | Very Low |
