Comparison of serum and urine ELISA methods for the diagnosis of Helicobacter pylori--a prospective pilot study

BACKGROUND/AIMS: Helicobacter pylori infection has a close relationship with many upper digestive tract diseases, but a gold standard for identifying this infection has not yet been well established, especially in clinical application. There is an increasing interest in non-invasive diagnostic tests. In this study, we will compare two non-invasive tests (ELISA method of urine and serum) in clinical use. METHODOLOGY: 170 patients (82 women, 88 men; mean age 52.4 yr) were included in this study and all underwent gastroendoscopy. None of the patients had received any H. pylori eradication therapy. The H. pylori infection status was evaluated by histology, culture, CLO test, and 13C-UBT. We also collected urine and serum for the ELISA method. H. pylori infection was defined as positive if the culture was positive or if two of the other three tests (histology, CLO test and 13C-UBT) were positive. If all four tests were negative or only one of the other three tests was positive, the result would be interpreted as negative. RESULTS: Of these 170 patients, 107 (62.94%) were H. pylori infected and 63 (37.06%) were uninfected. The sensitivity, specificity, positive predictive value and negative predictive value of serum ELISA were 96.26%, 74.60%, 86.55%, and 92.16% respectively; while those of urine ELISA were 93.46%, 92.06%, 95.24% and 89.23% respectively. There was no significant difference between these two tests in sensitivity, but urine ELISA has better specificity than serum ELISA significantly. CONCLUSIONS: Urine ELISA is a better non-invasive test for H. pylori infection than serum ELISA in clinical practice, because no blood need be drawn, it is safer, easier, and more convenient for sampling and has better specificity. Therefore it would be suitable in epidemiological screening of H. pylori infection, especially in young children, older patients and those who cannot cooperate.