Table 2.
Test characteristics of the Biocentric platform at two VL threshold levels
| At 2.62 log10 copies/mL | At 3.0 log10 copies/mL | |||||
|---|---|---|---|---|---|---|
| LAB-1 (n = 198) |
LAB-2 (n = 166) |
Combined (n = 364) |
LAB-1 (n = 198) |
LAB-2 (n = 166) |
Combined (n = 364) |
|
| Sensitivity % (95% CI) |
92.3 (64.0–99.8) | 84.4 (73.1–92.2) | 85.7 (75.9–92.6) | 100 (71.5–100) | 86.4 (75.0–94.0) | 88.6 (78.7–94.9) |
| Specificity % (95% CI) |
96.2 (92.4–98.5) | 99.0 (94.7–100) | 97.2 (94.6–98.8) | 97.9 (94.6–99.4) | 99.1 (94.9–100.0) | 98.3 (96.1–99.4) |
| ROC area % (95% CI) |
0.94 (0.87–1.00) | 0.92 (0.87–0.96) | 0.92 (0.87–0.96) | 0.99 (0.98–1.00) | 0.93 (0.88–0.97) | 0.93 (0.90–0.97) |
| PPV (at 10%)a % (95% CI) |
73.1 (56.3–85.1) | 90.5 (57.6–98.5) | 77.4 (63.2–87.2) | 83.9 (66.3–93.2) | 91.1 (59.3–98.6) | 85.3 (70.7–93.3) |
| NPV (at 10%)a % (95% CI) |
99.1 (94.5–99.9) | 98.3 (97.0–99.0) | 98.4 (97.3–99.1) | 100 (93.3–100) | 98.5 (97.2–99.2) | 98.7 (97.6–99.3) |
| PPV (at 20%)a % (95% CI) |
85.9 (74.4–92.8) | 95.6 (75.3–99.3) | 88.5 (79.4–93.9) | 92.1 (81.6–96.9) | 95.9 (76.6–99.4) | 92.9 (84.5–96.9) |
| NPV (at 20%)a % (95% CI) |
98.0 (88.4–99.7) | 96.2 (93.5–97.8) | 96.5 (94.0–97.9) | 100 (86.1–99.9) | 96.7 (93.9–98.2) | 97.2 (94.7–98.5) |
ROC Receiver operating characteristic, PPV Positive predictive value, NPV Negative predictive value
aFor the calculation of predictive values, 10 and 20% prevalence of detectable VLs were assumed in a hypothetical population undergoing routine VL testing