Helicobacter pylori breath testing in an open access system has a high rate of potentially false negative results due...

Among available tests to detect Helicobacter pylori (H. pylori), urea breath test (UBT) is the most accurate when performed correctly in research protocols with unknown validity in clinic settings.

A total of 595 subjects at a gastroenterology clinic were tested 620 times with UBT. Detailed information about three known factors (recent proton-pump inhibitors (PPI), antibiotics, or bismuth, H. pylori eradication treatment finished <4 weeks ago, and gastric resection) to make UBT unreliable were prospectively recorded before each test.

Twenty-three percent (120 of 526) of all negative tests fell in one or more of the three categories, which had the potential to make UBT unreliable. Of those carried out on persons without being treated before, the potential false negative rate was 15%. Among those with previous eradication treatment, the rate was around 45%.

If a negative UBT could be false negative in up to 23% of cases, then it has a serious lack of negative predictive value. A negative UBT should be considered false negative until potential protocol violations are excluded.