Evaluation of the two immunochromatographic methods for detecting urine and serum IgG antibodies to Helicobacter pylori and comparison of accuracy and clinical utility

Background/Aims: To evaluate the accuracy and clinical utility of two immunochromatographic methods, the STAT-PAK and RAPIRUN tests, in detecting H. pylori antibodies in serum and in urine separately. Methodology: 130 patients undergoing gastroendoscopy (70 men and, 60 women; mean age, 50.6 years) were enrolled in this study. Their H. pylori status was determined based on 4 tests: CLO test, culture, histology and UBT test. The H. pylori positive status was confirmed when the culture was positive, or 2 of the other 3 tests were positive. Serum samples and urine samples were collected. We used the STAT-PAK test for detecting H. pylori antibodies in serum, and read the results 24 hours later. Antibodies were also detected in urine by the RAPIRUN test, with a reading time of 25 minutes. 3 doctors read the results of both tests separately, and a positive result was determined when at least 2 of the doctors read a positive result. Results: In the STAT-PAK pretest using serum samples from 21 randomly selected patients (16 patients with H. pylori infection and 5 patients without infection), the sensitivity at 1-hour and 24-hour reading time was 18.7% and 37.5%. Specificity in both reading times was the same at 100%. Of 129 patients, 82 (64%) were H. pylori infected and 47 (36%) were uninfected. The sensitivity, specificity, and positive and negative predictive values were 31.7%, 93.6%, 89.6% and 44.0% in the STAT-PAK test with a 24-hour reading time, and 93.9%, 85.1%, 91.6%, 88.8% in the RAPIRUN test. One female was excluded because of an invalid urine test. Conclusions: The urine RAPIRUN test is a faster and more accurate office-based test than the serum STAT-PAK test for detecting the H. pylori infection in untreated patients in Taiwan. The non-invasive urine RAPIRUN test can be used as a large scale screening test for H. pylori status, particularly in children, uncooperative patients, those who have a family history of gastric cancer, or patients who can not tolerate the suffering of endoscopic examination.