Table 1.
Clinical performance of galactomannan EIA when testing plasma and serum samplesa
| Parameter | Performance comparison for each pair of sample types with: |
|||
|---|---|---|---|---|
| Plasma testing |
Serum testingb |
|||
| Proven/probable IA vs no IFD | Possible IA vs no IFD | Proven/probable IA vs no IFD | Possible IA vs no IFD | |
| Sensitivity (%; 95% CI) | 6/7 (85.7; 48.7–97.4) | 4/10 (40; 16.8–68.7) | 6/7 (85.7; 48.7–97.4) | 0/10 (0; 0–27.8) |
| Specificity (%; 95% CI) | 41/48 (85.4; 72.8–92.8) | 41/48 (85.4; 72.8–92.8) | 38/48 (79.2; 65.7–88.3) | 38/48 (79.2; 65.7–88.3) |
| PPV (%; 95% CI) | 6/13 (46.2; 23.2–70.9) | 10/17 (36.4; 15.2–64.6) | 6/16 (37.5; 18.5–61.4) | 0/10 (0; 0–27.8) |
| NPV (%; 95% CI) | 41/42 (97.6; 87.7–99.6) | 41/47 (87.2; 74.8–94.0) | 38/39 (97.4; 86.8–99.6) | 38/48 (79.2; 65.7–88.3) |
| LR+ | 5.88 | 2.74 | 4.11 | 1.26 |
| LR− | 0.17 | 0.70 | 0.18 | |
| DOR | 35.14 | 3.91 | 22.8 | |
Proven/probable cases (n = 1/6), possible cases (n = 10), and no-invasive fungal disease (IFD) controls (n = 48) were defined using the revised EORTC/MSG criteria with serum GM EIA or Aspergillus respiratory culture used as the microbiological criterion. The one case of proven IA was negative by GM EIA in serum and plasma. It was diagnosed as a proven case of IFD, with lung tissue showing septate hyphae with a 45° branching angle, and A. fumigatus was cultured from a respiratory sample. Of the 6 probable cases, 4 were serum GM EIA positive only and 2 were serum GM EIA positive and respiratory culture positive. Possible cases had radiological evidence specific to IA but were lacking microbiological evidence. PPV, positive predictive value; NPV, negative predictive value; LR+, likelihood ratio positive; LR−, likelihood ratio negative; DOR, diagnostic odds ratio.
As serum is a disease-defining criterion, an incorporation bias is introduced in favor of serum testing and is evident when analyzing data involving probable cases.