Table 4. Overall analytical sensitivity and specificity and agreement analysis of LAMP assay in comparison with real-time PCR assay (N = 333).
| Real-time PCR | MTB LAMP positive | NTM LAMP positive | LAMP negative | Total | |
|---|---|---|---|---|---|
| Comparison | MTB | 72 | 0 | 0 | 72 (21.6%) |
| NTM | 121 | 2 | 123 (36.9%) | ||
| Negative | 138 | 138 (41.4%) | |||
| Total | 72 (21.6%) | 121 (36.3%) | 140 (42.0%) | ||
| Comparison for pulmonary specimens (N = 264) | MTB | 59 | 0 | 0 | 59 (22.3%) |
| NTM | 118 | 2 | 120 (45.5%) | ||
| Negative | 85 | 85 (32.2%) | |||
| Total | 59 (22.3%) | 118 (44.7%) | 87 (33.0%) | ||
| Overall strength comparing with real-time PCR for pulmonary specimens (N = 264) | Analytical sensitivity | 98.88% (96.02–99.86) | |||
| Analytical specificity | 100% (95.75–100) | ||||
| NPV | 97.70% (91.46–99.41) | ||||
| PPV | 100% (NA) | ||||
| Overall strength comparing with real-time PCR (N = 333) | Analytical sensitivity | 98.97% (96.34–99.88) | |||
| Analytical specificity | 100% (97.36–100) | ||||
| NPV | 98.57% (94.56–99.64) | ||||
| PPV | 100% (NA) | ||||
| Agreement analysis* | Weighted Kappa (95% CI) | 0.9925 (0.9821–1.0000) | |||
| Standard error | 0.0053 | ||||
| Indicators | Overall (95% CI) | ||||
*Kappa agreement analysis applied.
Abbreviations: LAMP, loop-mediated isothermal amplification assay; MTB, Mycobacterium tuberculosis; NTM, Non-tuberculosis Mycobacterium; CI, confidence interval, NPV, negative predictive value, PPV, positive predictive value.