Table 1.
Baseline characteristics, clinical risk factors for thrombocytosis, and myeloid NGS result.
| Characteristics of cohort | Secondary thrombocytosis N = 160 | Essential thrombocythemia (ET) N = 176 | p value |
|---|---|---|---|
| Age (years; mean ± SD)∗ | 56 ± 17 | 69 ± 15 | <0.0001 |
| Gender: male (%), female (%) | 28 (18.5), 132 (82.5) | 65 (36.9), 111 (63.1) | |
| BMI (kg/m2; mean ± SD) | 30 ± 8.3 | 27 ± 5.4 | <0.0003 |
| WBC (×109 cells/L; mean ± SD) | 13.2 ± 11.9 | 9.4 ± 4.1 | <0.0001 |
| Hemoglobin (g/L; mean ± SD) | 122.9 ± 21.9 | 131.8 ± 17.8 | <0.0001 |
| MCV (fL; mean ± SD) | 87.7 ± 7.8 | 90.41 ± 9.236a | 0.0049 |
| RDW (%; mean ± SD), (N = 145, 152) | 15.3 ± 2.5 | 15.5 ± 2.5 | 0.3710 |
| MPV (fL; mean ± SD) | 9.2 ± 0.9 | 9.6 ± 1.1 | <0.0004 |
| Platelet count (×109 cells/L; mean ± SD) | 562 ± 141 | 803 ± 284 | <0.0001 |
| Change in platelet count (×109 cells/L; mean ± SD)∗∗ | 87 ± 223 | −226 ± 350 | <0.0001 |
| ANC (×109 cells/µL; mean ± SD) | 8.2 ± 7.3 | 6.5 ± 3.4 | 0.0058 |
| Ferritin (μg/L; mean ± SD) | 172 ± 320 | 148 ± 154 | 0.4522 |
|
| |||
| Clinical risk factors for thrombocytosis ∗∗∗ | |||
| Smoking, n (%) | 68 (53) | 65 (37) | 0.2113 |
| Arterial, venous thrombosis, n (%) | 16 (10), 5 (3) | 39 (22), 9 (5) | 0.0026, 0.3623 |
| Prior splenectomy, n (%) | 10 (63) | 3 (1.7) | 0.0310 |
| Active malignancy, n (%) | 11 (6.9) | 4 (2.3) | 0.0413 |
| Chronic inflammatory disease, n (%) | 19 (11.9) | 7 (4.0) | 0.0068 |
| Iron deficiency anemia, n (%) | 25 (15.6) | 12 (6.8) | 0.0100 |
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| Myeloid NGS results | |||
| JAK2 V617F; CALR Type 1 and Type 2; MPL | NA | 95 (54), 31 (18), 20 (11), 16 (9), ∗∗∗∗ | |
| Triple negative, n (%) | NA | 9 (5) | |
| Other myeloid mutations, n (%)∗∗∗∗ | 15 (9.7) | 29 (16.5) | 0.0539 |
| ASXL1, 3 (1.9) | TET2, 7 (4.0) | ||
| DNMT3A, 7 (4.4) | ASXL1, 5 (2.8) | ||
| Other 5 (3.1) | SF3B1, 5 (2.8) | ||
| Other 12 (6.8) | |||
∗ Age was determined at the time of NGS testing. ∗∗Change in platelet count included a total of 75 patients (23 in the ET group and 52 in the secondary thrombocytosis group) with evaluable data and excludes any patients on cytoreductive therapy. ∗∗∗Patients may have multiple secondary causes. ∗∗∗∗Some patients may have multiple mutations (3 patients in the secondary thrombocytosis had multiple mutations and 25 patients in the ET group had a second mutation alongside their driver mutation). aMCV was calculated on the 159 patients not on any cytoreductive therapy at the time of NGS testing (17 patients were on hydroxyurea). BMI, body mass index; WBC, white blood cells; MCV, mean corpuscular volume; RDW, red cell distribution width; MPV, mean platelet volume; ANC, neutrophil count; JAK2, Janus Kinase 2 gene; CALR, Calreticulin gene; MPL, thrombopoietin receptor protein gene.