Published online Jul 21, 2018. doi: 10.3748/wjg.v24.i27.3021
Peer-review started: April 28, 2018
First decision: June 11, 2018
Revised: June 12, 2018
Accepted: June 27, 2018
Article in press: June 27, 2018
Published online: July 21, 2018
To assess the diagnostic accuracy of a new fecal test for detecting Helicobacter pylori (H. pylori), using13C-urea breath test as the reference standard, and explore bacterial antibiotic resistance.
We conducted a prospective two-center diagnostic test accuracy study. We enrolled consecutive people≥ 18 years without previous diagnosis of H. pylori infection, referred for dyspepsia between February and October 2017. At enrollment, all participants underwent 13C-urea breath test. Participants aged over 50 years were scheduled to undergo upper endoscopy with histology. Participants collected stool samples 1-3 d after enrollment for a new fecal investigation (THD fecal test). The detection of bacterial 23S rRNA subunit gene indicated H. pylori infection. We also used the index diagnostic test to examine mutations conferring resistance to clarithromycin and levofloxacin. Independent investigators analyzed index test and reference test standard results blinded to the other test findings. We estimated sensitivity, specificity, positive (PPV) and negative (NPV) predictive value, diagnostic accuracy, positive and negative likelihood ratio (LR), together with 95% confidence intervals (CI).
We enrolled 294 consecutive participants (age: Median 37.0 years, IQR: 29.0-46.0 years; men: 39.8%). Ninety-five (32.3%) participants had a positive13C-urea breath test. Twenty-three (7.8%) participants underwent upper endoscopy with histology, with a full concordance between 13C-urea breath test and histology in detecting H. pylori infection. Four (1.4%) out of the 294 participants withdrew from the study after the enrollment visit and did not undergo THD fecal testing. In the 290 participants who completed the study, the THD fecal test sensitivity was 90.2% (CI: 84.2%-96.3%), specificity 98.5% (CI:96.8%-100%), PPV 96.5% (CI: 92.6%-100%), NPV 95.6% (CI: 92.8%-98.4%), accuracy 95.9% (CI: 93.6%-98.2%), positive LR 59.5(CI: 19.3-183.4), negative LR 0.10 (CI: 0.05-0.18). Out of 83 infected participants identified with the THD fecal test, 34 (41.0%) had bacterial genotypic changes consistent with antibiotic-resistant H. pylori infection. Of these, 27 (32.5%) had bacterial strains resistant to clarithromycin, 3 (3.6%) to levofloxacin, and 4 (4.8%) to both antibiotics.
The THD fecal test has high performance for the non-invasive diagnosis of H. pylori infection while additionally enabling the assessment of bacterial antibiotic resistances.
Core tip: Existing studies on molecular tests for Helicobacter pylori (H. pylori) detection in stools show suboptimal quality. The THD fecal test is a newer method to detect bacterial DNA and mutations conferring antibiotic resistance. In this diagnostic test accuracy study involving unselected consecutive participants and blinded outcome assessment, we evaluated the diagnostic accuracy of the THD fecal test for detecting H. pylori, using the 13C-urea breath test as the reference standard. We found that the THD fecal test has high performance for the non-invasive diagnosis of H. pylori infection while additionally enabling the assessment of bacterial antibiotic resistances.