Baseline characteristics and complete response at 1 week in both groups
| . | IVIg group . | Observation group . | ||||
|---|---|---|---|---|---|---|
| Complete response at 1 wk (n = 68) . | No complete response at 1 wk (n = 31) . | P value . | Complete response at 1 wk (n = 23) . | No complete response at 1 wk (n = 77*) . | P value . | |
| Male | 35 (51.5) | 18 (58.1) | .54 | 16 (69.6) | 39 (50.6) | .11 |
| Age at diagnosis, y | 4.3 (0.3-16.1) | 3.5 (1.1-14.2) | .44 | 3.9 (0.9-16.6) | 4.8 (0.5-16.5) | .44 |
| Duration symptoms at diagnosis, d | 3 (1-60) | 4 (1-30) | .17 | 1.5 (1-14) | 5 (0-60) | <.001 |
| Platelet count at diagnosis, ×109/L | 6 (0-20) | 5 (1-19) | .13 | 7 (1-20) | 5 (0-19) | .74 |
| Preceding infection | 42 (62.7) | 13 (41.9) | .05 | 18 (81.8) | 33 (43.4) | .002 |
| Preceding vaccination | 1 (1.5) | 2 (6.5) | .23 | 1 (4.5) | 4 (5.3) | 1.00 |
| Mucosal bleeding, grade 3 | 26 (38.8) | 12 (38.7) | .99 | 10 (45.5) | 32 (41.6) | .74 |
| Leukocyte count, ×109/L | 8.7 (4.5-17.5) | 8.1 (4.9-15.5) | .49 | 7.9 (4.4-18.3) | 8.0 (4.0-18.6) | .86 |
| Lymphocyte count, ×109/L | 3.9 (1.3-12.6) | 4.5 (1.4-9.1) | .80 | 3.9 (1.3-14.0) | 3.5 (0.9-11.0) | .74 |
| FCGR2B† | .03 | .02 | ||||
| 232II | 52 (77.6) | 21 (67.7) | 17 (100) | 47 (73.4) | ||
| 232IT | 15 (22.4) | 7 (22.6) | 0 (0) | 17 (26.6) | ||
| 232TT | 0 | 3 (9.7) | 0 (0) | 0 (0) | ||
| . | IVIg group . | Observation group . | ||||
|---|---|---|---|---|---|---|
| Complete response at 1 wk (n = 68) . | No complete response at 1 wk (n = 31) . | P value . | Complete response at 1 wk (n = 23) . | No complete response at 1 wk (n = 77*) . | P value . | |
| Male | 35 (51.5) | 18 (58.1) | .54 | 16 (69.6) | 39 (50.6) | .11 |
| Age at diagnosis, y | 4.3 (0.3-16.1) | 3.5 (1.1-14.2) | .44 | 3.9 (0.9-16.6) | 4.8 (0.5-16.5) | .44 |
| Duration symptoms at diagnosis, d | 3 (1-60) | 4 (1-30) | .17 | 1.5 (1-14) | 5 (0-60) | <.001 |
| Platelet count at diagnosis, ×109/L | 6 (0-20) | 5 (1-19) | .13 | 7 (1-20) | 5 (0-19) | .74 |
| Preceding infection | 42 (62.7) | 13 (41.9) | .05 | 18 (81.8) | 33 (43.4) | .002 |
| Preceding vaccination | 1 (1.5) | 2 (6.5) | .23 | 1 (4.5) | 4 (5.3) | 1.00 |
| Mucosal bleeding, grade 3 | 26 (38.8) | 12 (38.7) | .99 | 10 (45.5) | 32 (41.6) | .74 |
| Leukocyte count, ×109/L | 8.7 (4.5-17.5) | 8.1 (4.9-15.5) | .49 | 7.9 (4.4-18.3) | 8.0 (4.0-18.6) | .86 |
| Lymphocyte count, ×109/L | 3.9 (1.3-12.6) | 4.5 (1.4-9.1) | .80 | 3.9 (1.3-14.0) | 3.5 (0.9-11.0) | .74 |
| FCGR2B† | .03 | .02 | ||||
| 232II | 52 (77.6) | 21 (67.7) | 17 (100) | 47 (73.4) | ||
| 232IT | 15 (22.4) | 7 (22.6) | 0 (0) | 17 (26.6) | ||
| 232TT | 0 | 3 (9.7) | 0 (0) | 0 (0) | ||
Data are numbers (%) or medians (lower-upper limit) unless otherwise specified. Duration of symptoms denotes the duration of symptoms at the moment of diagnosis of ITP. Preceding infection: an infection within 28 d before diagnosis. Preceding vaccination: a vaccination within 28 d before diagnosis.
FCGR, IgG-Fc receptor.
For 1 patient in the observation group at 1 wk no exact platelet count was available but based on a platelet count of 38 × 109/L at 1 mo a count <100 × 109/L was assumed.
Blood samples for multiplex ligation probe amplification were available for 98/99 patients in the IVIg group with available response data and for 81/100 patients in the observation group.