Table 2.

Demographic characteristics of the studies.

Study	Year	Country	Type of study	Length of study	Sample size, n	Males, n (%)	Age (year, median)
Kim et al. [12]	2015	Korea	Retrospective	2003–2013	47	38 (80.9)	–
van de Putte et al. [13]	2015	–	Retrospective	1990–2014	51	36 (70.6)	63
Galsky et al. [14]	2015	USA	Retrospective	2005–2012	146	115 (78.8)	63
Gandhi et al. [15]	2015	USA	Retrospective	2000–2013	150	123 (82)	62.5
Chau et al. [16]	2015	UK	Retrospective	2005–2011	83	60 (72.3)	68
Khaled et al. [17]	2014	Egypt	RCT	2000–2002	59	44 (74.6)	54.2
Fairey et al. [18]	2013	USA	Retrospective	1985–2011	58	44 (75.9)	67
Pal et al. [19]	2012	USA	Retrospective	1995–2012	24	19 (79.2)	77.3
Matsubara et al. [20]	2012	Japan	Retrospective	2005–2010	25	15 (60)	67
Scosyrev et al. [21]	2012	USA	Retrospective	1999–2009	25	18 (72)	65
Kaneko et al. [22]	2011	Japan	Retrospective	2007–2011	22	16 (72.7)	69
Dash et al. [7]	2008	USA	Retrospective	2000–2006	42	32 (76.2)	64
Herchenhorn et al. [23]	2007	Brazil	Prospective	2002–2005	22	19 (86.4)	63

RCT, randomized control trial; –, not available.