Role of seroconversion in confirming cure of Helicobacter pylori infection

Context.-The role of serologic testing to confirm cure of Helicobacter pylori infection after antimicrobial therapy is not completely defined. Objective.-To determine the utility of serologic testing in confirming cure of H pylori infection more than 1 year after therapy. Design.-A prospective, before-after interventional trial. Setting.-An outpatient clinical research laboratory in an academic, urban Veterans Affairs medical center. Participants.-Twenty-three otherwise healthy men and women with active H pylori infection demonstrated by gastric biopsy and with positive H pylori serologic findings. Intervention.-A 14-day course of bismuth, tetracycline, and metronidazole. Main Outcome Measures.-Determination of IgG serum antibodies to H pylori at baseline, 1 month, 3 months, and approximately 18 months after completion of therapy compared with serial gastric mucosal biopsy specimens with stains for H pylori and for histologic examination as the criterion standard. Results.-Fifteen (65%) of 23 subjects were cured of their H pylori infection as assessed by gastric biopsy, with elimination of gastritis; median antibody levels declined from 92.5 U/mL at baseline to undetectable levels at 18 months. The other 8 subjects (35%) were not cured and had persistent gastritis at 18 months; median antibody levels declined from 130.6 U/mL at baseline to 89.7 U/mL at 18 months. Sensitivity and specificity of seroconversion (from a positive to negative test result) in detecting cure of H pylori infection were 60% and 100%, respectively. Conclusion.-Undetectable antibody levels beyond the first year of therapy accurately confirm cure of H pylori infection in initially seropositive healthy subjects, with reasonable sensitivity.