The data are consistent with the SRA having a high sensitivity for HIT (> 95%); the specificity of the SRA depends on the clinical situation, but in most circumstances is at least 90%. Patients in studies “A” and “B” were tested in both the polyspecific and IgG-specific assays. Data used to construct this table were obtained from the published literature.3,19–21
NA indicates not available.
*For the data shown, the cutoff for a positive SRA was 20% serotonin release. For study A (post-orthopedic surgery), if instead a 50% serotonin-release cutoff is used, the comparisons (polyspecific EIA) yield similar results: 11 of 20 versus 1 of 62 (P < .0001), and unchanged data for study B (VTE patients).
†For the VTE study, EIA results were ≥ 1.0 units of OD.