Objective: To determine the Helicobacter pylori IgG serology pattern 12-21 months after successful organism eradication and to assess the usefulness of IgG serology in the long-term follow-up of patients.
Methods: We recruited patients from our 1990-91 study on IgG serology after H. pylori treatment. Forty-three of 45 patients (93%) agreed to participate. They had all been cured of H. pylori infection after triple antibiotic therapy and remained H. pylori negative at 1 yr posttreatment. H. pylori IgG antibody concentrations were measured in serum samples taken at 3-month intervals between 12 and 21 months posttreatment. [13C]-urea breath test was done at each blood draw to ensure continued eradication. Serology was determined by ELISA (Pylori Stat, BioWhittaker, Inc) and expressed as absorbance.
Results: All 43 patients (100%) continued to be free of H. pylori and demonstrated a decline in their H. pylori IgG concentration compared with baseline. The overall decline in serology among all 43 patients was approximately 50%. Forty of 43 patients (93%) had a decline of more than 20% in H. pylori IgG concentration compared with baseline. However, 28 of 43 patients (65%) remained seropositive for more than 1 yr after successful H. pylori eradication.
Conclusion: We conclude that a 20% decline in IgG concentration has an overall sensitivity of 93% for determining H. pylori eradication 12-21 months after H. pylori treatment. Serology is an attractive alternative to endoscopy or urea breath tests in monitoring patients after H. pylori treatment, but serum IgG levels should not be expected to reach seronegative range after successful H. pylori eradication.