Table 1.

Scores of QI items.

Study Design (SD)	Score
Cross-sectional (CS)	1
Cases and controls (CC)	2
Cohorts (CHO)	3
Experimental (Exp)	4
Sample Size (N)
15 ≤ N < 30	1
30 ≤ N < 50	2
N ≥ 50	3
Bias Control (BC)
Completed	1
No completed	0