Table 3.

Study Quality Assessment Using the QATQS

Terms of bias	Degrees of Bias Risk	n (%)
Selection bias	Strong	0 (0.0)
	Moderate	6 (85.7)
	Weak	1 (14.3)
Study design	Strong	7 (100.0)
	Moderate	0 (0.0)
	Weak	0 (0.0)
Confounders	Strong	0 (0.0)
	Moderate	5 (71.4)
	Weak	2 (28.6)
Blinding	Strong	0 (0.0)
	Moderate	0 (0.0)
	Weak	7 (100.0)
Data collection methods	Strong	7 (100.0)
	Moderate	0 (0.0)
	Weak	0 (0.0)
Withdraws and dropouts	Strong	5 (71.4)
	Moderate	2 (28.6)
	Weak	0 (0.0)

Notes: QATQS = Quality Assessment Tool for Quantitative Studies.