Role of Helicobacter pylori serology in evaluating treatment success.

Duodenal ulcer recurrence and gastritis are reduced with successful Helicobacter pylori treatment. Serology is accurate in the diagnosis of H. pylori, but its value in determining eradication is unproved. To evaluate the usefulness of serology in monitoring treatment, we measured serial serum antibodies in three patient groups: eradication success (N = 57), eradication failure (N = 19), and untreated patients (N = 24). Eradication was determined by Warthin Starry staining of antral biopsies and repeat 13C breath tests at six weeks. Subsequent 13C breath tests were then performed at three-month intervals to monitor eradication. IgG antibody concentrations to H. pylori were determined by a commercially available ELISA kit. Serology concentrations remained constant throughout the study period in the untreated patients. IgG concentrations decreased slightly in the treatment failure group at six weeks but thereafter remained at baseline values. In the eradicated group, serum IgG concentrations decreased 26% by three months, 43% by six months and 55% at nine and 12 months (P < 0.001). A 20% reduction in IgG concentrations by six months was associated with successful treatment (sensitivity 86% and specificity 88%). We conclude that serology is a potentially useful way to monitor H. pylori treatment success.