Figure 17 - Model of the relationship among lower esophageal sphincter pressure (x axis), size of hernia (y axis), and the susceptibility to gastroesophageal reflux induced by provocative maneuvers that increase abdominal pressure as reflected by the reflux score (z axis).

The statistical model was created by stepwise regression analysis of the data in Figure 16. The overall equation for the model is as follows: reflux score = 22.64 + 12.05 (hernia size) – 0.83 (LES pressure) – 0.65 (LES pressure hernia size). The multiple correlation coefficient of this equation for the 50 subject data set was 0.86 (R² = .75), indicating that 75% of the observed variance in susceptibility to stress reflux among individuals was accounted for by the size of hiatus hernia and the instantaneous value of LES pressure. (Source: Sloan et al.,⁵⁰ with permission from American College of Physicians.)