A comparative study on routine diagnostic methods in infection of Helicobacter pylori

Objective To investigate the efficacy of the four commonly used diagnostic methods in infection of Helicobacter pylori(H. pylori). Methods The study included 133 patients with upper gastrointestinal symptoms. Three fresh gastric biopsy were extracted from the lesser curvature of antrum when patients accepting gastroscopy, for the rapid urease test(RUT) test strip, RUT gel method, and histological examination, respectively.14C-urease breath test(14C-UBT) was carried out 1 hour after the procedure. The result of histological examination was served as the golden reference.Any two tests positive were served as the relative golden reference.The diagnostic accuracy of the four methods and the consistence with golden reference and relative golden reference was evaluated. Results The positive results were obtained in 111 cases by RUT test strip, 76 by RUT gel method, 70 by 14C-UBT, and 62 by Warthin—Starry stain. With Warthin—Starry positive as the golden reference, the finding of RUT test strip was poorly consistent with the result of Warthin—Starry(Kappa=0.295). However, the findings of RUT gel method and 14C-UBT were highly consistent with the result of Warthin—Starry(Kappa=0.672, 0.670). Because of the poor specificity of RUT test strip, any two positive tests from Warthin—Starry, RUT gel method and 14C-UBT were used as the relative golden reference to evaluate the diagnostic accuracy. The findings of Warthin—Starry and 14C-UBT were perfectly consistent with the golden reference(Kappa=0.821, 0.850), and the finding of RUT gel method was highly consistent with the golden reference(Kappa=0.763). However, the finding of RUT test strip was poorly consistent with golden reference(Kappa=0.280). When the delta cutoff value for the UBT was calculated as a standard value(DMP≥100), the area under the ROC curve was 0.932 (0.884-0.979), and the sensitivity, specificity and accuracy of 14C-UBT were 100.0%, 86.3% and 92.5%, respectively.When the delta cutoff value for the UBT was recalculated as a new value(DMP≥166), the area under the ROC curve increased to 0.949(0.906-0.992). With the golden reference as the evaluation, the sensitivity, specificity and accuracy of UBT test were 96.7%, 93.2% and 94.7%, respectively. Conclusion RUT test strip shows low accuracy; RUT gel method, UBT and histological examination have high accuracy and similar efficacy. When the delta cutoff value for the test is recalculated as DMP≥166, the accuracy of the test can be improved. Key words: Helicobacter pylori; Rapid urease test; Histology; Urease breath test