Jinan Univ;
Coll Med;
Affiliated Hosp 2;
Dept Gastroenterol;
Shenzhen 518001;
Guangdong;
Peoples R China;
Milan Univ Hosp;
Div Gastroenterol;
Milan;
Italy;
esophagitis/etiology; gastric; acid/secretion; duodenal; ulcer/etiology; gastroesophageal; reflux/etiology; hydrogen; ion; concentration; multivariate; analysis;