Table 3 Criteria of GRADE quality analysis

Grade A

(high value)

Randomized clinical study or a prospective study with a well-defined control group;

Clear definition of diagnosis and endpoints;

Description of diagnostic reliability tests and reproducibility tests;

Blinding of outcome assessment.

Grade B

(moderate value)

Cohort study or retrospective study with a well-defined control group;

Clear definition of diagnosis and endpoints;

Description of diagnostic reliability tests and reproducibility tests.

Grade C

(low value)

Large attrition;

Unclear definition of diagnosis and endpoints;

Ill-defined patient material.