Table 2. Clinical and laboratory characteristics of 167 patients with essential thrombocythemia according to the mutational status of JAK2 and CALR.

Characteristic	JAK2+/CALR+ (A)	JAK2+/CALR- (B)	JAK2-/CALR+ (C)‡	JAK2-/CALR- (D) ‡	P value
					AvsB	AvsC	AvsD	BvsC	BvsD	CvsD
Patients, n (%)	7 (4)	103 (62)	19 (11)	38 (23)	-	-	-	-	-	-
Male, n†	3	53	10	13	0.714	1.000	0.686	1.000	0.087	0.253
Age at onset, years, SE (med; ran)*	7.0(62;29-77)	1.2(63;6-87)	3.3(62;25-80)	2.9(52;11-80)	0.783	0.977	0.511	0.619	0.008	0.152
WBC count, × 109/L, SE(med; ran)*	1.5(8.4;3.6–16.9)	0.7(12.7;5.1–59.6)	0.8(9.5;4.5–18.8)	0.5(9.0;4.4–18.3)	0.006	0.355	0.594	0.002	<0.0001	0.286
Hemoglobin, g/dL, SE(med; ran)*	0.83(13.4;9.6–15.1)	0.20(13.9;8.4–19.5)	0.33(13.5;10.1–15.9)	0.32(12.3;6.6–17.1)	0.225	0.685	0.707	0.188	0.0003	0.080
Platelet count, × 109/L, SE(med; ran)*	110(1006;471-1186)	24(933;487-1935)	97(1021;557-2232)	50(998;456-1648)	0.995	0.355	0.719	0.089	0.566	0.306
Lactate dehydrogenase, mU/mL, SE(med; ran)*	88(486;185–969)	19(557;192–1157)	48(481;200–1000)	31(462;195–932)	0.233	0.885	0.835	0.272	0.026	0.478
Splenomegaly, n (%)†	3 (43)	35 (34)	7 (37)	4 (11)	0.691	1.000	0.064	0.799	0.006	0.031
Thrombotic events, n (%)†	0	32 (31)	3 (16)	3 (8)	0.104	0.540	1.000	0.270	0.004	0.389
Plateletpheresis, n (%)†	4 (57)	34 (33)	8 (42)	12 (32)	0.232	0.665	0.225	0.444	1.000	0.558
Transformation to secondary MF or AL, n (%)†	0	7 (7)	0	0	1.000	N/A	N/A	0.594	0.190	N/A

n, number; SE, standard error; med, median; ran, range; WBC, white blood cell; MF, myelofibrosis; AL, acute leukemia; N/A, not applicable.

^*P values were calculated using the Mann-Whitney U test.

^†P values were calculated using the Fisher's exact test.

^‡Group C and D were all negative for MPL exon 10 mutation.