Table 3. Diagnostic accuracy of immunoassays according to PAT result.
| Immunoassay | TP | FN | FP | TN | Sensitivity | Specificity | Difference in specificity | Likelihood ratio | |
|---|---|---|---|---|---|---|---|---|---|
|
Percent (95%CI) |
p<0.05 compared to |
Positive (95%CI) |
Negative (95%CI) |
||||||
| PaGIA | |||||||||
| Low threshold (Positive/ negative) |
12 | 0 | 27 | 132 | 100.0 (73.5, 100.0) |
83.0 (76.3, 88.5)) |
AcuStar HIT-IgG | 5.9 (4.2, 8.3) |
0.0 |
| Intermediate threshold (Titre of 4) |
12 | 0 | 7 | 152 | 100.0 (73.5, 100.0) |
95.6¶ (91.1, 98.2) |
22.7 (11.0, 46.9) |
0.0 | |
| High threshold (Titre of 32) |
12 | 5 | 0 | 159 | 58.3 (27.7, 84.8) |
100.0# (97.7, 100.0) |
>1000 | 0.29 | |
| Polyspecific ELISA (GTI) | |||||||||
| Low threshold (OD 0.4) |
12 | 0 | 24 | 108 | 100.0 (73.5, 100.0) |
81.8 (74.2, 88.0) |
AcuStar HIT-IgG | 5.5 (3.8, 7.9) |
0.0 |
| Intermediate threshold (OD 1.3) |
12 | 0 | 4 | 128 | 100.0 (73.5, 100.0) |
96.8¶ (92.4, 99.2) |
33.0 (12.6, 86.6) |
0.0 | |
| High threshold (OD 2.0) |
12 | 0 | 3 | 132 | 100.0 (73.5, 100.0) |
97.7 (93.5, 99.5) |
44.0 (14.4, 130.0) |
0.0 | |
| AcuStar HIT-IgG | |||||||||
| Low threshold (1.0 U/ml) |
13 | 0 | 12 | 154 | 100.0 (75.3, 100.0) |
92.8 (87.7, 96.2) |
PaGIA, ELISA | 13.8 (8.0, 23.9) |
0.0 |
| Intermediate threshold (2.8 U/ml) |
13 | 0 | 4 | 162 | 100.0 (75.3, 100.0) |
97.6¶ (94.0, 99.3) |
41.5 (15.8, 110.0) |
0.0 | |
| High threshold (9.4 U/ml) |
11 | 2 | 1 | 165 | 84.6 (54.6, 98.1) |
99.4 (96.7, 100.0) |
140.5 (19.6, 1000.0) |
0.15 (0.04, 0.55) |
|
TP, true positives; FN, false negatives; FP, false positives; TN, true negatives
¶ p<0.05 for difference in specificity compared to low threshold
# p<0.05 for difference in specificity compared to intermediate threshold