ABSTRACT
OBJECTIVE: The 13C-urea breath test is the main non-invasive test for the diagnosis of Helicobacter pylori infection. The availability of this test throughout the country is limited, mainly due to the difficulty in obtaining the labeled isotope from abroad. Recently, researchers from the Nuclear Energy Center in Agriculture at the University of São Paulo (CENA/USP) succeeded in synthesizing 13C-enriched urea for Helicobacter pylori diagnosis. The aim of the study was to compare the performance of the 13C-urea breath test using 13C-urea acquired abroad with that of a test using 13C-urea synthesized in Brazil. METHOD: Sixty-four dyspeptic patients participated in the study (24 men and 40 women). Initially, the patients performed the 13C-urea breath test using the imported substrate (Euriso-Top, France). Seven to fourteen days later, all the patients repeated the test using the Brazilian substrate. The samples from both examinations were processed in an infrared isotope analyzer (IRIS, Wagner Analisen Technik, Germany), and all delta over baseline (DOB) [%] values above four were considered positive results. RESULTS: Twenty-seven patients (42%) exhibited negative results for Helicobacter pylori infection, and thirty-seven patients (58%) exhibited positive results when tested using the foreign substrate (gold standard). There was a 100% concordance regarding the presence or absence of infection when the gold standard results were compared with those obtained using the Brazilian substrate. CONCLUSIONS: Similar performance in the diagnosis of Helicobacter pylori infection was demonstrated when using the 13C-urea breath test with the Brazilian 13C-urea substrate and the test with the substrate produced abroad. This validation represents an important step toward increasing the availability of the 13C-urea breath test throughout the country, which will have a positive influence on the management of Helicobacter pylori infection.
Subject(s)
Humans , Male , Female , Adult , Middle Aged , Aged , Aged, 80 and over , Urea/analysis , Urea/chemical synthesis , Carbon Isotopes/analysis , Carbon Isotopes/chemical synthesis , Helicobacter Infections/diagnosis , Reference Values , Time Factors , Brazil , Breath Tests/methods , Reproducibility of Results , Helicobacter pylori/isolation & purification , Statistics, NonparametricABSTRACT
The aim of this study was to validate the rapid lateral flow Helicobacter pylori stool antigen test (One step H. pylori antigen test, ACON laboratories, San Diego, USA; Prime diagnostics, São Paulo), using 13C-Urea Breath Test as the gold standard for H. pylori infection diagnosis. A total of 98 consecutive patients, asymptomatic or dyspeptic, entered the study. Sixty-nine were women, with a mean age of 45.76 ± 14.59 years (14 to 79 years). In the H. pylori-positive group, the rapid stool antigen test detected H. pylori antigen in 44 of the 50 positive patients (sensitivity 88 percent; 95 percent CI: 75.7-95.5 percent), and six false-negative; and in the H. pylori-negative group 42 presented negative results (specificity 87.5 percent; 95 percent CI: 74.7-95.3 percent), and six false-positive, showing a substantial agreement (Kappa Index = 0.75; p < 0.0001; 95 percent CI: 0.6-0.9). Forty four of fifty patients that had positive stool antigen were H. pylori-positive, the PPV of the stool antigen test was 88 percent (95 percent CI: 75.7-95.5 percent), and 42 patients with negative stool antigen test were H. pylori-negative, the NPV of the stool antigen test was 87.5 percent (95 percent CI: 74.7-95.3 percent). We conclude that the lateral flow stool antigen test can be used as an alternative to breath test for H. pylori infection diagnosis especially in developing countries.
O objetivo desse trabalho foi avaliar o teste rápido de antígeno de H. pylori nas fezes (One step H. pylori antigen test, ACON laboratories, San Diego, USA; Prime diagnostics, São Paulo), usando teste respiratório com uréia marcada com 13C (TRU-13C), como padrão ouro. Noventa e oito pacientes assintomáticos ou com dispepsia participaram do estudo. Sessenta e nove eram mulheres; a média de idade dos pacientes foi de 45.76 ± 14.59 (14 a 79 anos). No grupo H. pylori positivo, o teste rápido detectou antígenos de H. pylori nas fezes em 44 dos 50 pacientes positivos (sensibilidade de 88 por cento; 95 por cento IC: 75.7-95.5 por cento), com seis falso-negativos; e no grupo H. pylori negativo, 42 apresentaram resultados negativos (especificidade de 87,5 por cento; 95 por cento IC: 74.7-95.3 por cento), com seis falso-positivos, mostrando concordância substancial (índice Kappa = 0.75; p < 0.0001; 95 por cento IC: 0.6-0.9). Quarenta e quatro dos 50 que tiveram teste de antígeno fecal positivo eram H. pylori positivos, sendo o VPP do teste 88 por cento (95 por cento IC: 75.7-95.5 por cento), e 42 pacientes com teste de antígeno fecal negativo eram H. pylori negativos, com VPN de 87,5 por cento (95 por cento IC: 74.7-95.3 por cento). Concluímos que o teste de antígeno fecal imunocromatográfico pode ser usado como alternativa ao teste respiratório para diagnóstico de infecção pelo H. pylori, principalmente em países em desenvolvimento.