Comparison of positivity of four serum antibody kits up to 6 years after Helicobacter pylori eradication

Abstract

Aim: Anti-Helicobacter pylori (H. pylori) antibody titers of four serum antibody kits were measured simultaneously up to 6 years in order to clarify the usefulness in the detection of past infection for the screening of gastric cancer risk and the possibility of unnecessary eradication in patients with successful eradication.

Subjects and methods: The study included 239 subjects (66.0 ± 9.3 years old, male 117, female 122) who were enrolled in a multicenter study. Serum samples were obtained at least three times during a 6-year period after successful eradication. Anti-H. pylori antibody titers were measured for each serum sample using three Latex aggregation immunoassay (LA) kits and one enzyme immunoassay (EIA) kit simultaneously, and the changes in antibody-positive rate were compared.

Results: Seropositivity of each kit at 1 to 6 years after eradication was as follows. LZ test: 58.9, 45.1, 45.0, 35.5, 38.7, and 40.4%. Denka latex “Seiken”: 63.9, 52.4, 39.6, 36.2, 35.1, and 27.7%. L-type Wako: 75.7, 61.6, 55.0, 53.9, 48.8, and 40.4%. E-plate (EIA kit): 72.8, 62.2, 48.6, 45.4, 38.7, and 34.0% when the cut-off value was set at 3.0 U/mL and 10.4, 4.3, 4.5, 5.7, 4.2, and 2.1% when cut-off value was set at 10.0 U/mL.

Conclusions: Compared to the EIA kit, antibody titers of the LA kits remained higher than cut-off value for longer years after eradication. LA kits might be more useful to identify past infection in mass surveys. However, serum antibodies are often measured in subjects after successful eradication. It is important to perform appropriate diagnostic tests to avoid unnecessary eradication when LA tests show positive results.