The accuracy of Helicobacter pylori antibody assays for 561 consecutive adult outpatients who had undergone gastroscopy was studied. The sensitivity of an immunoglobulin G test was 99 to 100% for all age groups, but the specificity declined by age group, from 99% for those aged 15 to 49 years to 75% for those aged >65 years. The exclusion of false-positive results for patients with atrophic gastritis improved the specificity to 93 to 97% for the older age groups.Helicobacter pylori infection is associated with gastritis, peptic ulcer disease, and gastric malignancies (1). In about onethird or up to one-half of those infected with H. pylori, gastritis proceeds to atrophic gastritis, resulting in a loss of mucosal glands, decreased helicobacter colonization and, when affecting the corpus mucosa, decreased secretion of pepsinogen I (PGI) (10, 23).Most helicobacter-infected subjects have specific circulating immunoglobulin G (IgG) antibodies. However, IgA antibodies are found in approximately two-thirds of infected subjects (9). Of infected individuals, 2 to 7% show an elevated level of IgA antibody only (5, 9). Patients with atrophic corpus gastritis often have positive helicobacter serology, although microscopic examination (6, 22), culture of biopsy samples, and even the urea breath test remain helicobacter negative (8). These particular patients may still be infected, as shown by rapidly falling antibody titers after therapy (7).Enzyme immunoassay (EIA) is the most commonly used serological method for detecting antibodies to H. pylori. The best commercial kits have shown sensitivities and specificities of 90% to in excess of 95% (3, 12 Biopsy samples. Gastroscopies were performed by one of the authors (A.S.-R.) in a routine manner, with two biopsies from the gastric antrum (2 cm or more from the pylorus), two biopsies from the large curve of the gastric corpus for histological examination, and additional biopsies (one from the antrum and one from the corpus) for culture.Formalin-fixed biopsy specimens were embedded in paraffin. Tissue sections of 3 m were cut at three levels per biopsy and placed on one slide. The tissue sections were stained with hematoxylin and eosin, Alcian blue (pH 2.5)-periodic acidSchiff, and modified Giemsa. Gastritis was classified according to the Sydney System, in a blinded fashion, by one pathologist (J.M.) (20).The biopsies were mailed for culture in Transpocult tubes (Orion Diagnostica, Espoo, Finland). The specimens were cultured for H. pylori for up to 12 days on Brucella agar plates (Becton Dickinson, Sparks, Md.) (18) supplemented with whole horse blood (7%) and on selective Brucella agar plates containing Iso-Vitalex (1%), vancomycin (6 mg/liter), amphotericin B (2 mg/liter), and nalidixic acid (20 mg/liter).Results were considered helicobacter positive if culture or histology or both were positive.Serum tests. Serum samples were taken during each patient's visit to the endoscopic unit and were stored at Ϫ20°C until analyzed. Sera were tested for H. pylori IgG and IgA antibodie...

This intervention with high participation rates resulted in a significant decline in calculated H. pylori seroprevalence rates. Although the low prevalence of H. pylori infection may limit the cost efficiency of the program, the intervention is expected to reduce the burden of H. pylori-associated diseases.