Table 1. Characteristics of included studies.

Lead Author	Year	Country	Sample Size	Female (%)	Mean Age (years)
Chiu [18]	2001	China	78	32.1	70.6
Chiu [20]	2002	China	340	30.3	69.0
Chiu [19]	2009	China	183	36.6	70.5
Hinarejos [17]	2013	Spain	2948	76.3	75.9
Sprowson [16]	2016	United Kingdom	848	74.5	82.6