Table 3. Performance Characteristics of HR-B/V Test vs Procalcitonin Measurement for the Diagnosis of Bacterial Infection Using a 4-Group Likelihood Scheme.
| Test and group | No./total No. (%) | % (95% CI) | Interval likelihood ratio (95% CI)c | ||||
|---|---|---|---|---|---|---|---|
| Bacterial infection | Viral infection | PPV in groupa | NPV in groupa | Sensitivityb | Specificityb | ||
| Primary analysis | |||||||
| HR-B/V test | |||||||
| VVL (probability score <0.19) | 2/49 (4.1) | 172/285 (60.4) | NA | 98.9 (96.1-100) | NA | 60.4 (54.7-66.0) | 0.07 (0-0.20) |
| VL (probability score 0.19-0.40) | 3/49 (6.1) | 62/285 (21.8) | NA | 95.4 (88.1-98.7) | NA | 21.8 (17.0-26.9) | 0.28 (0-0.77) |
| BL (probability score 0.41-0.73) | 18/49 (36.7) | 36/285 (12.6) | 33.3 (22.9-48.3) | NA | 36.7 (23.4-50.8) | NA | 2.91 (1.76-4.74) |
| BVL (probability score >0.73) | 26/49 (53.1) | 15/285 (5.3) | 63.4 (47.2-77.9) | NA | 53.1 (38.8-67.4) | NA | 10.08 (5.69-17.36) |
| Procalcitonin measurement | |||||||
| BVU (<0.10 ng/mL) | 22/49 (44.9) | 187/285 (65.6) | NA | 89.5 (84.6-93.1) | NA | 65.6 (59.9-70.6) | 0.68 (0.49-0.94) |
| BU (0.10-0.24 ng/mL) | 13/49 (26.5) | 61/285 (21.4) | NA | 82.4 (72.0-90.4) | NA | 21.4 (17.1-26.8) | 1.24 (0.72-2.12) |
| BL (0.25-0.50 ng/mL) | 4/49 (8.2) | 13/285 (4.6) | 23.5 (6.7-50.0) | NA | 8.2 (2.3-18.3) | NA | 1.79 (0.41-5.82) |
| BVL (>0.50 ng/mL) | 10/49 (20.4) | 24/285 (8.4) | 29.4 (15.9-45.6) | NA | 20.4 (10.3-33.9) | NA | 2.42 (1.17-4.90) |
| Secondary analysis | |||||||
| HR-B/V test | |||||||
| VVL (probability score <0.19) | 8/117 (6.8) | 238/499 (47.7) | NA | 96.7 (94.2-98.4) | NA | 47.7 (43.6-52.3) | 0.14 (0.07-0.27) |
| VL (probability score 0.19-0.40) | 8/117 (6.8) | 121/499 (24.2) | NA | 93.8 (87.9-96.9) | NA | 24.2 (20.7-28.5) | 0.28 (0.12-0.56) |
| BL (probability score 0.41-0.73) | 36/117 (30.8) | 95/499 (19.0) | 27.5 (20.0-35.7) | NA | 30.8 (22.6-39.7) | NA | 1.62 (1.19-2.27) |
| BVL (probability score >0.73) | 65/117 (55.6) | 45/499 (9.0) | 59.1 (49.7-67.9) | NA | 55.6 (46.5-63.9) | NA | 6.16 (4.55-8.59) |
| Procalcitonin measurement | |||||||
| BVU (<0.10 ng/mL) | 53/117 (45.3) | 332/499 (66.5) | NA | 86.2 (82.7-89.5) | NA | 66.5 (61.9-70.8) | 0.68 (0.54-0.82) |
| BU (0.10-0.24 ng/mL) | 27/117 (23.1) | 104/499 (20.8) | NA | 79.4 (71.7-85.6) | NA | 20.8 (17.7-24.7) | 1.11 (0.74-1.59) |
| BL (0.25-0.50 ng/mL) | 11/117 (9.4) | 30/499 (6.0) | 26.8 (15.0-42.8) | NA | 9.4 (5.1-15.9) | NA | 1.56 (0.75-3.02) |
| BVL (>0.50 ng/mL) | 26/117 (22.2) | 33/499 (6.6) | 44.1 (30.4-57.1) | NA | 22.2 (15.4-30.5) | NA | 3.36 (2.06-5.24) |
Abbreviations: BL, bacterial likely; BU, bacterial unlikely; BVL, bacterial very likely; BVU, bacterial very unlikely; HR-B/V, host response bacterial/viral; NA, not applicable; NPV, negative predictive value; PPV, positive predictive value; VL, viral likely; VVL, viral very likely.
PPV and NPV were used for the diagnosis of bacterial infection.
Sensitivity and specificity were calculated as the percentage of adjudicated participants in each band. The test’s overall sensitivity and specificity were calculated as the sum of values in the respective cells. For example, the HR-B/V test had a sensitivity of 89.8% (53.1% plus 36.7%) for results in the BVL or BL groups and a specificity of 82.2% (60.4% plus 21.8%) for results in the VVL or VL groups.
Likelihood ratios were used for the diagnosis of bacterial infection. Values in the BVL and BL groups correspond to positive likelihood ratios, whereas values in the VL and VVL correspond to negative likelihood ratios.