Table 2.
Mean DOB, sensitivities, specificities, positive and negative predictive values, and accuracies of 13C-urea breath test with or without test meals in the gray zone (Value of 13C-UBT: 4.0–10.0‰).
| Without citric acid (n = 24) | Low-dose citric acid (n = 24) | P value | Without citric acid (n = 13) | High-dose citric acid (n = 13) | P value | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Self-control* (30 min) | 15 min | 30 min | Self-control vs. 15 min | Self-control vs. 30 min | 15 min vs. 30 min | Self-control* (30 min) | 15 min | 30 min | Self-control vs. 15 min | Self-control vs. 30 min | 15 min vs. 30 min | |
| DOB( +) (mean ± SD) | 7.75 ± 1.79 | 24.28 ± 18.99 | 20.08 ± 13.90 | < 0.0001 | < 0.0001 | 0.052 | 6.85 ± 1.98 | 28.91 ± 13.90 | 32.91 ± 14.76 | 0.008 | 0.008 | 0.219 |
| DOB(-) (mean ± SD) | NA(n = 0) | 0.51 ± 0.47 | 1.08 ± 1.14 | NA | NA | 0.469 | NA(n = 0) | 0.38 ± 0.34 | 0.84 ± 0.97 | NA | NA | 0.375 |
| Sensitivity (%) | 100.0% (18/18) | 94.4% (17/18) | 100.0% (18/18) | > 0.999 | > 0.999 | > 0.999 | 100.0% (8/8) | 100.0% (8/8) | 100.0% (8/8) | > 0.999 | > 0.999 | > 0.999 |
| Specificity (%) | 0% (0/6) | 100.0% (6/6) | 100.0% (6/6) | 0.002 | 0.002 | > 0.999 | 0% (0/5) | 100.0% (5/5) | 100.0% (5/5) | 0.008 | 0.008 | > 0.999 |
| PPV (%) | 75.0% (18/24) | 100.0% (17/17) | 100.0% (18/18) | 0.033 | 0.029 | > 0.999 | 61.5% (8/13) | 100.0% (8/8) | 100.0% (8/8) | 0.111 | 0.111 | > 0.999 |
| NPV (%) | NA(0/0) | 85.7% (6/7) | 100.0% (6/6) | NA | NA | > 0.999 | NA(0/0) | 100.0% (5/5) | 100.0% (5/5) | NA | NA | > 0.999 |
| Accuracy (%) | 75.0% (18/24) | 95.8% (23/24) | 100.0% (24/24) | 0.097 | 0.022 | > 0.999 | 61.5% (8/13) | 100.0% (13/13) | 100.0% (13/13) | 0.039 | 0.039 | > 0.999 |
*(Self-control 30 min): commercial 13C-UBT that breath samples were taken at 30 min without citric acid.
(+): H. pylori status gold standard positive; (−): H. pylori status gold standard negative.
NA not applicable.