The Diagnostic Validity of Citric Acid-Free, High Dose 13C-Urea Breath Test After Helicobacter pylori Eradication in Korea

Abstract

Background

The 13C-urea breath test (13C-UBT) is a noninvasive method for diagnosing Helicobacter pylori (H. pylori) infection. The aims of this study were to evaluate the diagnostic validity of the 13C-UBT cutoff value and to identify influencing clinical factors responsible for aberrant results.

Methods

13C-UBT (UBiTkit; Otsuka Pharmaceutical, cutoff value: 2.5‰) results in the range 2.0‰ to 10.0‰ after H. pylori eradication therapy were compared with the results of endoscopic biopsy results of the antrum and body. Factors considered to affect test results adversely were analyzed.

Results

Among patients with a positive 13C-UBT result (2.5‰ to 10.0‰, n = 223) or a negative 13C-UBT result (2.0‰ to < 2.5‰, n = 66) after H. pylori eradication, 73 patients (34.0%) were false positive, and one (1.5%) was false negative as determined by endoscopic biopsy. The sensitivity, specificity, false-positive rate, and false-negative rate for a cutoff value of 2.5‰ were 99.3%, 47.1%, 52.9%, and 0.7%, respectively, and positive and negative predictive values of the 13C-UBT were 67.3% and 98.5%, respectively. Multivariate analysis showed that a history of two or more previous H. pylori eradication therapies (OR = 2.455, 95%CI = 1.299–4.641) and moderate to severe gastric intestinal metaplasia (OR = 3.359, 95%CI = 1.572–7.178) were associated with a false-positive 13C-UBT result.

Conclusion

The 13C-UBT cutoff value currently used has poor specificity for confirming H. pylori status after eradication, and this lack of specificity is exacerbated in patients that have undergone multiple prior eradication therapies and in patients with moderate to severe gastric intestinal metaplasia. In addition, the citric-free 13C-UBT would increase a false-positive 13C-UBT result.