Cutoff Pepsinogen Level for Predicting Unintendedly Eradicated Cases of Helicobacter pylori Infection in Subjects with Seemingly Normal Pepsinogen Levels

In the ABC method, which is a method for risk stratification of gastric cancer using serum anti-Helicobacter pylori antibody and pepsinogen (PG) test, subjects with normal PG and seronegative for H. pylori are named as "Group A" and are regarded as having a low risk of gastric cancer. These "Group A" subjects include unintentionally eradicated cases at relatively high risk, and this study aimed to identify these subjects.Of the 109 subjects, 76 were classified as uninfected Group A subjects with negative histologic H. pylori infection and no histologic and endoscopic atrophy, and 33 subjects were classified serologically as Group A after successful eradication, which are serologically equal to the unintendedly eradicated cases in Group A. The usefulness of measuring PG levels to detect post-eradication cases was validated by using a receiver operating characteristic (ROC) curve analysis.The area under the ROC curve for PGI level was 0.736 ± 0.06 (p0.01; cutoff value, 37.0 ng/mL; sensitivity, 77.6%; specificity, 72.7%), and that for the PGI/II ratio was 0.660 ± 0.06 (p0.01; cutoff value, 5.1; sensitivity, 84.2%; specificity, 43.4%).PGI levels of ≤37 ng/mL and PGI/II ratios of ≤5.1 effectively identified unintendedly eradicated cases in Group A.