Table 1.

Characteristics of included papers (in general population).

Author	Area of origin	Population	Year of publication	Diagnosed criteria	Number of investigated people	Number of patients	Quality score
Zhao et al. [10]	Five cities in China	18–80 years	2011	Rome II	16078	948	7
Cheng et al. [6]	Hong Kong	18–80 years	2003	Rome II	3282	458	7
Wei et al. [11]	Guangzhou City	>18 years	2001	Rome II	2892	108	5
Xiong et al. [8]	Guangdong Province	18–80 years	2004	Rome II	3931	159	6
Shen et al. [68]	Shanghai City	18–97 years	2012	Rome III	7648	211	4
Kan et al. [9]	Tianjin City	>18 years	2003	<3 BMs/week	7220	838	5
Tang et al. [69]	Anhui Province	>18 years	2008	Rome III	3709	139	4
Zuo and Han [70]	Henan Province	2–92 years	2012	Rome III	6102	1108	4
Shi et al. [7]	Xinjiang Autonomous Region	>10 years	2010	Rome II	1354	285	4
Lv et al. [71]	Nanchang City	10–91 years	2005	Rome II	3745	122	4
Guo et al. [72]	Beijing City	18–70 years	2001	Rome II	2486	151	6
Xiang et al. [73]	Chongqing City	>18 years	2004	Rome II	1492	47	4
Zhang et al. [74]	Sichuan Province	11–90 years	2008	Rome II	2912	96	5
Zhang et al. [75]	Henan Province	General population	2008	<3 BMs/week	1838	163	4
Liu et al. [76]	Hangzhou City	1 y–99 years	2004	<2 BMs/week	5107	899	4