Table 2. Diagnostic accuracy of LF-LAM among HIV clinic attendees with CD4<200.
| Prevalence of TB | Prevalence of positive LAM | Sensitivity | Specificity | PPV | NPV | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gold standard = confirmed* and clinical† TB | n/N | % | n/N | % | n/N | % (95% CI) | n/N | % (95% CI) | n/N | % (95% CI) | n/N | % (95% CI) |
| Grade 1‡ cut-off | 56/424 | 13.2% | 24/424 | 5.7% | 8/56 | 14.3% (6.4, 26.2) | 352/368 | 95.7% (93.0, 97.5) | 8/24 | 33.3% (15.6, 55.3) | 352/400 | 88.0% (84.4, 91.0) |
| CD4 <100 | 35/187 | 18.7% | 12/187 | 6.4% | 6/35 | 17.1% (6.6, 33.6) | 146/152 | 96.1% (91.6, 98.5) | 6/12 | 50.0% (21.1, 78.9) | 146/175 | 83.4% (77.1, 88.6) |
| CD4 ≥100 | 21/237 | 8.9% | 12/237 | 5.1% | 2/21 | 9.5% (1.2, 30.4) | 206/216 | 95.4% (91.7, 97.8) | 2/12 | 16.7% (2.1, 48.4) | 206/225 | 91.6% (87.1, 94.8) |
| Grade 2§ cut-off | 56/424 | 13.2% | 8/424 | 1.9% | 3/56 | 5.4% (1.1, 14.9) | 363/368 | 98.6% (96.9, 99.6) | 3/8 | 37.5% (8.5, 75.5) | 363/416 | 87.3% (83.7, 90.3) |
| Gold standard = confirmed* TB (all clinical† TB excluded) (N = 408) | ||||||||||||
| Grade 1‡ cut-off | 40/408 | 9.8% | 21/408 | 5.1% | 5/40 | 12.5% (4.2, 26.8) | 352/368 | 95.7% (93.0, 97.5) | 5/21 | 23.8% (8.2, 47.2) | 352/387 | 91.0% (87.6, 93.6) |
| CD4 <100 | 24/176 | 13.6% | 10/176 | 5.7% | 4/24 | 16.7% (4.7, 37.4) | 146/152 | 96.1% (91.6, 98.5) | 4/10 | 40.0% (12.2, 73.8) | 146/166 | 88.0% (82.0, 92.5) |
| CD4 ≥100 | 16/232 | 6.9% | 11/232 | 4.7% | 1/16 | 6.3% (0.2, 30.2) | 206/216 | 95.4% (91.7, 97.8) | 1/11 | 9.1% (0.2, 41.3) | 206/221 | 93.2% (89.1, 96.2) |
| Grade 2§ cut-off | 40/408 | 9.8% | 8/408 | 2.0% | 3/40 | 7.5% (1.6, 20.4) | 363/368 | 98.6% (96.9, 99.6) | 3/8 | 37.5% (8.5, 75.5) | 363/400 | 90.8% (87.5, 93.4) |
* Confirmed TB = positive on Xpert MTB/RIF or line probe assay or M. tuberculosis culture, from any sample taken within 6 months of enrolment
† Clinical TB = started TB treatment within 6 months of enrolment, in the absence of microbiological confirmation and those smear-positive in the absence of an associated culture
‡ Grade 1 positive: > = 1+
§ Grade 2 positive: > = 2+
NPV = Negative predictive value; PPV = Positive predictive value; CI = confidence interval