Urine-based enzyme-linked immunosorbent assay for the detection of Helicobacter pylori infection in children

Objective. Serology and C-13-urea breath test have been widely used as noni nvasive tests to detect Helicobacter pylori infection. However, easier coll ection of samples and lower costs are desirable for diagnosis of the indivi dual patient or for use in epidemiologic studies. Our aim was to study the diagnostic accuracy of a recently developed urine-based enzyme-linked immun osorbent assay (ELISA) kit for the detection of H pylori-specific immunoglo bulin G (IgG) antibodies in children. Study Design. Specimens of serum and randomly voided urine were collected f rom 816 children (0-15 years old) and were analyzed using 2 serum-based ELI SA kits and a urine-based ELISA kit, respectively. Based on results of sero logy, the sensitivity, specificity, and accuracy of the urine-based ELISA k it were evaluated. With regard to false-positive and false-negative results , urinary IgG concentrations and IgG/creatinine levels were studied. Results. Both serum-based ELISAs were positive in 41 children and were nega tive in 666, who were enrolled in this study. The remaining 109 children we re excluded because of disagreement between the results of the 2 serum-base d ELISAs, including indeterminate values. Overall sensitivity, specificity, and accuracy of urine-based ELISA test compared with serology were 85.4%, 95.5%, and 94.9%, respectively. On positivity rates, the urine-based ELISA was closely coincident with the serum-based ELISA in each age group. There was no correlation between antibody levels detected by urine-based ELISA an d each serum-based ELISA. Urinary IgG concentrations and IgG/creatinine lev els were significantly higher in false-positives and were lower in false-ne gatives than in true-positives plus true-negatives for serology. Most of th ose with false-positive results had trace to moderate proteinuria. Conclusions. The urine-based ELISA is an alternative to serum-based ELISA f or diagnosis of H pylori infection in children and should be suitable for l arge-scale epidemiologic studies concerning the organism. In children with proteinuria, results of the test should be interpreted with caution. It is possible that the urine-based ELISA method would be applicable to diagnosis of other infectious diseases.