Performance characteristics of laboratory assays used in VITT screening of referred patients based on PF4-SRA results
| Assay performed . | Sensitivity (95% CI) . | Specificity (95% CI) . | PPV (95% CI) . | NPV (95% CI) . |
|---|---|---|---|---|
| Immunoassays | ||||
| Commercial IgG/A/M anti-PF4/heparin EIA | 100% (91.8-100) | 95.6% (90.0-98.6) | 89.6% (78.5-95.3) | 100% |
| In-house IgG anti-PF4-EIA | 100% (91.8-100) | 96.5% (91.2-99.0) | 91.5% (80.4-96.6) | 100% |
| In-house IgG anti-PF4/heparin-EIA | 100% (91.8-100) | 97.4% (92.4-99.5) | 93.5% (82.4-97.8) | 100% |
| Functional assays | ||||
| Standard SRA* | 16.7% (7.0-31.4) | 100% (96.4-100) | 100% | 74.3% (71.6-76.8) |
| PF4/Heparin-SRA* | 46.2% (26.6-66.6) | 100% (59.0-100) | 100% | 33.3% (26.0-41.7) |
| Assay performed . | Sensitivity (95% CI) . | Specificity (95% CI) . | PPV (95% CI) . | NPV (95% CI) . |
|---|---|---|---|---|
| Immunoassays | ||||
| Commercial IgG/A/M anti-PF4/heparin EIA | 100% (91.8-100) | 95.6% (90.0-98.6) | 89.6% (78.5-95.3) | 100% |
| In-house IgG anti-PF4-EIA | 100% (91.8-100) | 96.5% (91.2-99.0) | 91.5% (80.4-96.6) | 100% |
| In-house IgG anti-PF4/heparin-EIA | 100% (91.8-100) | 97.4% (92.4-99.5) | 93.5% (82.4-97.8) | 100% |
| Functional assays | ||||
| Standard SRA* | 16.7% (7.0-31.4) | 100% (96.4-100) | 100% | 74.3% (71.6-76.8) |
| PF4/Heparin-SRA* | 46.2% (26.6-66.6) | 100% (59.0-100) | 100% | 33.3% (26.0-41.7) |
PPV, positive predictive value; NPV, negative predictive value; CI, confidence interval.
Tested on a smaller VITT patient cohort (SRA n = 153, PF4/hep-SRA n = 33) compared with other assays (n = 156).