Comparison of the distribution of the times to seroconversion between HIT and antibody-positive non-HIT control patients
| Type of antibody . | Patients with HIT . | Non-HIT antibody-positive controls . | P . | ||
|---|---|---|---|---|---|
| n . | Days to seroconversion, mean (SD) . | n . | Days to seroconversion, mean (SD) . | ||
| From day of beginning postoperative heparin | |||||
| IgG | 12 | 4.75 (0.93) | 34 | 6.03 (2.09) | .0018 |
| IgA | 7 | 6.57 (5.29) | 16 | 6.37 (5.72) | .855 |
| IgM | 4 | 7.50 (9.00) | 12 | 6.00 (6.00) | .412 |
| IgG/A/M | 12 | 4.25 (1.11) | 36 | 4.47 (2.14) | .574 |
| From day of surgery | |||||
| IgG | 12 | 5.92 (0.81) | 34 | 7.12 (1.80) | .0017 |
| IgA | 7 | 7.86 (5.48) | 16 | 7.50 (5.07) | .740 |
| IgM | 4 | 8.75 (10.92) | 12 | 7.08 (6.81) | .407 |
| IgG/A/M | 12 | 5.42 (0.81) | 36 | 5.55 (1.85) | .690 |
| Type of antibody . | Patients with HIT . | Non-HIT antibody-positive controls . | P . | ||
|---|---|---|---|---|---|
| n . | Days to seroconversion, mean (SD) . | n . | Days to seroconversion, mean (SD) . | ||
| From day of beginning postoperative heparin | |||||
| IgG | 12 | 4.75 (0.93) | 34 | 6.03 (2.09) | .0018 |
| IgA | 7 | 6.57 (5.29) | 16 | 6.37 (5.72) | .855 |
| IgM | 4 | 7.50 (9.00) | 12 | 6.00 (6.00) | .412 |
| IgG/A/M | 12 | 4.25 (1.11) | 36 | 4.47 (2.14) | .574 |
| From day of surgery | |||||
| IgG | 12 | 5.92 (0.81) | 34 | 7.12 (1.80) | .0017 |
| IgA | 7 | 7.86 (5.48) | 16 | 7.50 (5.07) | .740 |
| IgM | 4 | 8.75 (10.92) | 12 | 7.08 (6.81) | .407 |
| IgG/A/M | 12 | 5.42 (0.81) | 36 | 5.55 (1.85) | .690 |
Data are shown separately for the commercial EIA (which detects antibodies of all 3 classes [IgG/A/M] against PF4/polyanion) and EIAs that detect antibodies of the 3 major immunoglobulin classes individually. Combining the data for the 48 patients (12 with HIT, 36 seropositive non-HIT controls), the median day of onset for the 3 immunoglobulin classes (with respect to the day of beginning heparin therapy) are as follows: IgG, day 6 (IQR, day 5-7; n = 46 seroconversions); IgA, day 6 (IQR, day 5-8; n = 23 seroconversions); and IgM, day 6 (IQR, day 5-9; n = 16 seroconversions).
HIT indicates heparin-induced thrombocytopenia; EIA, enzyme-immunoassay; and IQR, interquartile range.