Table 2.

Classification of the extracted articles according to the design of the study.

Study design	Frequency	(%)
Meta-analysis	5	0.32
Systematic reviews	200	12.85
Randomized controlled trials	103	6.62
Clinical trials	75	4.81
Cohort studies	16	1.02
Case-control studies	24	1.54
Cross-sectional studies	1005	64.55
Case reports	119	7.64
Case series	10	0.64
Total	1557	100