The association between the pepsinogen I/II ratio and the risk of moderate or severe esophageal squamous dysplasia. The pepsinogen I/II ratio was plotted on a linear scale, from high to low, and the odds of ESD was plotted on a logarithmic scale. The vertical dotted lines demarcate the quartiles (the 75th, 50th, and 25th percentiles, respectively) of the PGI/II ratio values.