28 HELICOBACTER PYLORI INFECTION: HOW CERTAIN IS SERODIAGNOSIS?

Abstract

Diagnosis of Helicobacter pylori (Hp) infection may be obtained by direct or indirect methods. In clinical practice serology titers are often used as they are easy to perform, cheap and non-invasive. However when local prevalence is high this method might overestimate the diagnosis due to previous contract with the germ. To assess this hypothesis in an area of high incidence of Hp infection in adults, we undertook a study comparing histology, microbiology and IgG titers in children. We evaluated 114 children (65M, 49F) referred for upper GI endoscopy due to abdominal symptoms, foreign body or caustic ingestion (without esophageal or gastric lesions). Antral biopsies were taken and sent for histology and culture. Blood samples were drawn for anti-Hp IgG assessment. Mean age was 6.5±3.9 yrs (0.5-13.5). The rate of infection in this group was 47.1% and there was a gradual increase with age. Histology and microbiology agreed in 97.5%. IgG titers were significantly higher in Hp positive children. When the 95% confidence limit was used as the cut-of value of IgG titer, sensitivity of serology was 79.6% and specificity was 78.2%. These results show that histology is appropriate to identify Hp infection and may be preferred to culture because it provides faster results and allows to detect associated lesions. In areas where Hp prevalence is high, serology test titer must be adapted to local basal levels. Even when this correction is made the diagnostic value of this method may be questionable in each individual patient. When diagnostic accuracy is required then direct methods like histology, culture of biopsy or the string entero-test must be used.