Evaluation of diagnostic accuracy of two rapid stool antigen tests using an immunochromatographic assay to detect Helicobacter pylori.

OBJECTIVES: The stool antigen assay for H. pylori infection diagnosis with monoclonal antibodies is a simple and recommended technique by the Maastricht V/Florence consensus report. Recently, Pylori K-Set K-1219 (Coris Bioconcept Sprl, Belgium) and HP-F23 (Symbiosys, Brazil) have been made commercially available in Brazil. Thus, the aim of this study was to evaluate the diagnostic accuracies of these two rapid stool antigen tests by immunochromatographic assays (index tests) for the clinical practice. DESIGN AND METHODS: A total of 98 patients who underwent upper gastrointestinal endoscopy and 13C-urea breath test entered the study. H. pylori infection status was defined by the combination of the rapid urease test and the 13C-urea breath test (reference standard). Two observers who were aware of H. pylori status performed the reading of index tests. Diagnostic accuracy (sensitivity, specificity, positive predictive value, negative predictive value with 95% confidence intervals, positive likelihood ratio, negative likelihood ratio and kappa index measure of agreement) were determined. RESULTS: The index tests where in perfect agreement with the H. pylori status with kappa values of 0.87 for Pylori K-Set K-1219 and 0.92 for HP-F23. The sensitivity of HP-F23 was 97.9% (IC95%: 87.5-100) and specificity was 93.8% (IC95%; 84-97.2).The positive likelihood ratio was 15.8, and the negative likelihood ratio was 0.02. The Pylori K-Set K-1219 had a sensitivity of 87.7% (IC95%: 74.5-94.9) and a specificity of 100% (IC95%: 91.6-100); the positive likelihood ratio was ∞, and the negative likelihood ratio was 0.1. The test line on the cassette device of HP-F23 was stronger than of the Pylori K-Set K-1219. CONCLUSION: The HP-F23 test performed better in clinical practice. Nonetheless, the 13C-urea breath test is more reliable technique. Moreover, caution must be paid to the trace or clear pale test line readings that were observed in false positive and false negative results, leading to incorrect management of the patient.

Hypolactasia is associated with insulin resistance in nonalcoholic steatohepatitis.

AIM: To assess lactase gene (LCT)-13910C>T polymorphisms in Brazilian non-alcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) patients in comparison with healthy controls. METHODS: This was a transverse observational clinical study with NAFLD patients who were followed at the Hepatology Outpatient Unit of the Hospital das Clínicas, São Paulo, Brazil. The polymorphism of lactase non-persistence/lactase persistence (LCT-13910C>T) was examined by PCR-restriction fragment length polymorphism technique in 102 liver biopsy-proven NAFLD patients (steatosis in 9 and NASH in 93) and compared to those of 501 unrelated healthy volunteers. Anthropometric, clinical, biochemical and liver histology data were analyzed. Continuous variables were compared using the t or Mann-Whitney tests, and categorical data were compared with the Fisher's exact test. Univariate logistic regression and multivariate logistic regression adjusted for gender and age were performed. RESULTS: No differences in the LCT-13910 genotype frequencies were noted between the NAFLD patients (66.67% of the patients with steatosis were CC, 33.33% were CT, and none were TT; 55.91% of the patients with NASH were CC, 39.78% were CT, and 4.3% were TT; P = 0.941) and the healthy controls (59.12% were CC, 35.67% were CT, and 5.21% were TT) or between the steatosis and NASH patients. That is, the distribution of the lactase non-persistence/lactase persistence polymorphism (LCT-13910C>T) in the patients with NAFLD was equal to that in the general population. In the NASH patients, the univariate analysis revealed that the lactase non-persistence (low lactase activity or hypolactasia) phenotype was associated with higher insulin levels (23.47 ± 15.94 µU/mL vs 15.8 ± 8.33 µU/mL, P = 0.027) and a higher frequency of insulin resistance (91.84% vs 72.22%, P = 0.02) compared with the lactase persistence phenotype. There were no associations between the LCT genotypes and diabetes (P = 0.651), dyslipidaemia (P = 0.328), hypertension (P = 0.507) or liver histology in these patients. Moreover, in the NASH patients, hypolactasia was an independent risk factor for insulin resistance even after adjusting for gender and age [OR = 5.0 (95%CI: 1.35-20; P = 0.017)]. CONCLUSION: The LCT-13910 genotype distribution in Brazilian NAFLD patients was the same as that of the general population, but hypolactasia increased the risk of insulin resistance in the NASH patients.