GAST and bile reflux: wherex1represents alcohol consumption (No denotes 0, Yes denotes 1), x2represents smoking (No denotes 0, Yes denotes 1), x3 represents family history (No denotes 0, Yes denotes 1), x4 represents HP infection (No denotes 0, Yes denotes 1), x5 represents pepsinogen I value, x6 represents pepsinogen II value, x7 represents gastrin 17 value, x8 represents bile reflux (No denotes 0, Yes denotes 1),x9 represents Kimura–Takemoto classification (C1, C2, C3), and the constant term of the formula (0.601) means reference intercept.