Table 3. Performance of RT-LAMP-LFD assay compared with the reference standard for detecting avian-origin influenza A (H7N9) virus.
| RT-LAMP-LFD | Reference standard | Performance characteristics (%) a | ||||||
| Positive | Negative | Total | Sensitivity | Specificity | PPV | NPV | ||
| HA | Positive | 22 | 0 | 22 | 100% | 100% | 100% | 100% |
| Negative | 0 | 58 | 58 | |||||
| Total | 22 | 58 | 80 | |||||
| NA | Positive | 22b | 0 | 22 | 100% | 100% | 100% | 100% |
| Negative | 0 | 58 | 58 | |||||
| Total | 22 | 58 | 80 | |||||
a
PPV, positive predictive value; NPV, negative predictive value.
b
One HA-positive while NA-negative sample detected by real-time RT-PCR was further confirmed to be H7N9 infection by viral culture and sequencing.