Table 2.

Methodological assessment of study quality by Oxford Center for Evidence-Based Medicine checklist

No	Studies	Criteria for methodological assessment of study quality
		A	B	C	D		E	F
					1	2
1	Jamileh Malakouti et al. (2017) ▶, Iran	+	-	+	+	+	+	+
2	Amiri Mina et al. (2014), Iran	+	+	+	+	+	+	+
3	Cindy M. Meston et al. (2008) ▶, USA	+	+	+	+	+	+	-
4	David Wheatley et al. (2004) ▶, UK	+	+	+	+	+	+	-
5	Byung-JoKang et al. (2002), South Korea	+	+	+	+	+	+	-