Is saliva serology useful for the diagnosis of Helicobacter pylori?

BACKGROUND: The Cortecs Diagnostics Helisal Assay test is a quantitative immunoassay for salivary IgG antibodies against Helicobacter pylori. Saliva can be obtained simply with the kit in the general practitioners surgery. AIMS: To compare the new saliva serological test for H pylori with 'gold standard' evidence of H pylori infection (antral biopsy specimens for histology, culture, and urease test) and a new serum serological test. PATIENTS: Eighty six unselected dyspeptic patients undergoing endoscopy. METHODS: Each patient provided saliva and serum before endoscopy for H pylori serology, which was compared against 'gold standard' evidence of infection. RESULTS: Thirty two patients were H pylori positive by the 'gold standard' tests. At a cut off value of 0.15 EU/ml the saliva test had a sensitivity of 88% and a specificity of 71%, with a negative predictive value of 90%. If patients who were taking omeprazole or had recent antibiotics are excluded, the sensitivity is unchanged but the specificity increases to 79%. The serum test had a similar sensitivity of 85% but better specificity of 78%. CONCLUSION: Serum testing remains the best serological test for H pylori in the hospital setting. Saliva testing may have a role in epidemiological studies and in screening dyspeptic patients in general practice, especially in children in whom venesection is more difficult.