表 2.
证据级别
| 级别 | 内容 |
| A级 | 经多次随机干预或荟萃分析证明 |
| B级 | 在单个随机临床试验或非大型随机干预的临床试验中得到证明 |
| C级 | 专家或小型临床试验的共识(包括回顾性研究和注册) |
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