Open Access Research article

Systematic investigation of gastrointestinal diseases in China (SILC): validation of survey methodology

Xiaoyan Yan1, Rui Wang1, Yanfang Zhao1, Xiuqiang Ma1, Jiqian Fang2, Hong Yan3, Xiaoping Kang4, Ping Yin5, Yuantao Hao2, Qiang Li3, John Dent6, Joseph Sung7, Duowu Zou8, Saga Johansson9, Katarina Halling9, Wenbin Liu10 and Jia He1*

Author Affiliations

1 Department of Health Statistics, Second Military Medical University, Shanghai, China

2 Department of Health Statistics, Zhongshan Medical University, Guangzhou, China

3 Department of Health Statistics, Xi'an Jiao Tong University, Xi'an, China

4 Department of Health Statistics, Peking University, Beijing, China

5 Department of Health Statistics, Huazhong Science and Technology University, Wuhan, China

6 Department of Gastroenterology, Hepatology & General Medicine, Royal Adelaide Hospital, Adelaide, SA, Australia

7 Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, China

8 Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China

9 AstraZeneca R&D, Mölndal, Sweden

10 R&D Medical Affairs, AstraZeneca Pharmaceutical Co Ltd., Shanghai, China

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BMC Gastroenterology 2009, 9:86  doi:10.1186/1471-230X-9-86

Published: 19 November 2009



Symptom-based surveys suggest that the prevalence of gastrointestinal diseases is lower in China than in Western countries. The aim of this study was to validate a methodology for the epidemiological investigation of gastrointestinal symptoms and endoscopic findings in China.


A randomized, stratified, multi-stage sampling methodology was used to select 18 000 adults aged 18-80 years from Shanghai, Beijing, Xi'an, Wuhan and Guangzhou. Participants from Shanghai were invited to provide blood samples and undergo upper gastrointestinal endoscopy. All participants completed Chinese versions of the Reflux Disease Questionnaire (RDQ) and the modified Rome II questionnaire; 20% were also invited to complete the 36-item Short Form Health Survey (SF-36) and Epworth Sleepiness Scale (ESS). The psychometric properties of the questionnaires were evaluated statistically.


The study was completed by 16 091 individuals (response rate: 89.4%), with 3219 (89.4% of those invited) completing the SF-36 and ESS. All 3153 participants in Shanghai provided blood samples and 1030 (32.7%) underwent endoscopy. Cronbach's alpha coefficients were 0.89, 0.89, 0.80 and 0.91, respectively, for the RDQ, modified Rome II questionnaire, ESS and SF-36, supporting internal consistency. Factor analysis supported construct validity of all questionnaire dimensions except SF-36 psychosocial dimensions.


This population-based study has great potential to characterize the relationship between gastrointestinal symptoms and endoscopic findings in China.