Dynamic analysis of area under the curve (AUC) estimation of hydrogen ion activity predicts mucosal damage in GERD

Gastroesophageal reflux disease (GERD) is caused by esophageal exposure to concentrated acid over time. We tested the hypothesis that AUC for hydrogen ion activity (H⁺) modeled by the power function, predicts mucosal damage and propose that GERD is a two component disease. In 33 continuous 24-h esophageal pH recordings (Hines VA Hospital) the AUC H⁺ was calculated and correlated with Savary-Miller grades of esophagitis. A functional relationship between the relative importance of AUC H⁺ and H⁺ was derived using the power function with two parameters (β1 and β2). The mean values of AUC H⁺ activity by endoscopic grade were significantly different (p<0.001, Kruskal-Wallis test). The lowest mean value corresponded to grade 1 and the highest to grade 4. The power function plot of each endoscopy grade shows two different patterns at low and high values of H⁺.