Adjustment of cut-off values in ELISA for detection of Helicobacter pylori infection.

AIM: to detect Helicobacter pylori infection in Indonesian patients.
METHODS: serum samples were collected from patients referred for upper endoscopy. Gastric biopsies were taken for polymerase chain reaction (PCR) examination. The gold standard for diagnosing H. pylori infection was 294 bp amplication target of PCR examination with primer ureC. The serum samples were tested for H. pylori antibodies using Biohit Anti-H. pylori ELISA according to the manufacturer instructions. By using analysis of receiver operating characteristic (ROC), an optimal cut-off point of serum IgG H.pylori and area under curve (AUC) ROC were determined. The accuracy of test was calculated according to a new cut-off value. Significance level was determined by p value <0.05.
RESULTS: a total of 81 patients were recruited, 31 (41.9%) subjects were H. pylori-positive. We found a new optimal cut-off point on serum IgG H.pylori at 15,2 IU/mL with AUC ROC of 0.84. By using the new cut-off value, we conclude that the Biohit Anti-H. pylori ELISA has a good sensitivity and specificity, i.e. 94.1% (95% CI 59.9 - 89.6) and 97.9% (95% CI 92.3 - 100.0) respectively.
CONCLUSION: by adjusting new cut-off values for Indonesian patients, we are able to improve the performance of Biohit Anti-H. pylori ELISA. This study illustrates the importance of local validation.