María J Ramírez-Lázaro1, Sergio Lario1, Xavier Calvet1, Jordi Sánchez-Delgado1, Antònia Montserrat1, Elisa M Quílez2, Alex Casalots3, David Suarez4, Rafel Campo1, Enric Brullet1, Félix Junquera1, Isabel Sanfeliu5, Ferran Segura6. 1. Digestive Diseases Department, Corporació Sanitària i Universitària Parc Taulí, Sabadell, Spain ; Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain ; Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Instituto de Salud Carlos III, Barcelona, Spain. 2. Digestive Diseases Department, Corporació Sanitària i Universitària Parc Taulí, Sabadell, Spain ; Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain. 3. Pathology Department, UDIAT-CD, Corporació Sanitària i Universitària Parc Taulí, Sabadell, Spain. 4. Epidemiology and Evaluation Unit, Fundació Parc Taulí- UAB, Sabadell, Spain. 5. Microbiology Laboratory, UDIAT-CD, Corporació Sanitària i Universitaria Parc Taulí, Sabadell, Spain ; Spanish Network for the Research in Infectious Diseases (REIPI RD06/0018), Sevilla, Spain. 6. Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain ; Spanish Network for the Research in Infectious Diseases (REIPI RD06/0018), Sevilla, Spain ; Infectious Diseases Department, Corporació Sanitària i Universitària Parc Taulí, Sabadell, Spain.
Abstract
BACKGROUND: In a previous study, UBiT-100 mg, (Otsuka, Spain), a commercial (13)C-urea breath test omitting citric acid pre-treatment, had a high rate of false-positive results; however, it is possible that UBiT detected low-density 'occult' infection missed by other routine reference tests. We aimed to validate previous results in a new cohort and to rule out the possibility that false-positive UBiT were due to an 'occult' infection missed by reference tests. METHODS: Dyspeptic patients (n = 272) were prospectively enrolled and UBiT was performed, according to the manufacturer's recommendations. Helicobacter pylori infection was determined by combining culture, histology and rapid urease test results. We calculated UBiT sensitivity, specificity, positive and negative predictive values (with 95% CI). In addition, we evaluated 'occult' H. pylori infection using two previously-validated polymerase chain reaction (PCR) methods for urease A (UreA) and 16 S sequences in gastric biopsies. We included 44 patients with a false-positive UBiT, and two control groups of 25 patients each, that were positive and negative for all H. pylori tests. RESULTS: UBiT showed a false-positive rate of 17%, with a specificity of 83%. All the positive controls and 12 of 44 patients (27%) with false-positive UBiT were positive for all two PCR tests; by contrast, none of our negative controls had two positive PCR tests. CONCLUSIONS: UBiT suffers from a high rate of false-positive results and sub-optimal specificity, and the protocol skipping citric acid pre-treatment should be revised; however, low-density 'occult' H. pylori infection that was undetectable by conventional tests accounted for around 25% of the 'false-positive' results.
BACKGROUND: In a previous study, UBiT-100 mg, (Otsuka, Spain), a commercial (13)C-urea breath test omitting citric acid pre-treatment, had a high rate of false-positive results; however, it is possible that UBiT detected low-density 'occult' infection missed by other routine reference tests. We aimed to validate previous results in a new cohort and to rule out the possibility that false-positive UBiT were due to an 'occult' infection missed by reference tests. METHODS: Dyspeptic patients (n = 272) were prospectively enrolled and UBiT was performed, according to the manufacturer's recommendations. Helicobacter pyloriinfection was determined by combining culture, histology and rapid urease test results. We calculated UBiT sensitivity, specificity, positive and negative predictive values (with 95% CI). In addition, we evaluated 'occult' H. pyloriinfection using two previously-validated polymerase chain reaction (PCR) methods for urease A (UreA) and 16 S sequences in gastric biopsies. We included 44 patients with a false-positive UBiT, and two control groups of 25 patients each, that were positive and negative for all H. pylori tests. RESULTS:UBiT showed a false-positive rate of 17%, with a specificity of 83%. All the positive controls and 12 of 44 patients (27%) with false-positive UBiT were positive for all two PCR tests; by contrast, none of our negative controls had two positive PCR tests. CONCLUSIONS:UBiT suffers from a high rate of false-positive results and sub-optimal specificity, and the protocol skipping citric acid pre-treatment should be revised; however, low-density 'occult' H. pyloriinfection that was undetectable by conventional tests accounted for around 25% of the 'false-positive' results.
Authors: Patrick M Bossuyt; Johannes B Reitsma; David E Bruns; Constantine A Gatsonis; Paul P Glasziou; Les M Irwig; David Moher; Drummond Rennie; Henrica C W de Vet; Jeroen G Lijmer Journal: Ann Intern Med Date: 2003-01-07 Impact factor: 25.391
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Authors: Patrick M Bossuyt; Johannes B Reitsma; David E Bruns; Constantine A Gatsonis; Paul P Glasziou; Les M Irwig; Jeroen G Lijmer; David Moher; Drummond Rennie; Henrica C W de Vet Journal: Ann Intern Med Date: 2003-01-07 Impact factor: 25.391
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