Table 1. Grades of Evidences.

Grades of Evidences	Description
Ia	Evidences are originated from the meta-analysis results of various RCTs
Ib	Evidences are originated from the results of at least one well-designed RCT
IIa	Evidences are originated from the results of at least one well-designed perspective non-RCT
IIb	Evidences are originated from the results of at least one well-designed interventional clinical research of other type
III	Evidences are originated from the well-designed non-interventional clinical researches, such as descriptive researches and relevant researches
IV	Evidences are originated from the reports made by committee of experts or the clinical reports of authoritative experts

Abbreviations: RCT, randomized controlled trial