Table 1.

Patients’ baseline characteristics

Characteristic	n (%) or median (range)
Age at WM diagnosis, years	61 (35-91)
Age at ibrutinib initiation, years	68 (40-96)
Age >65 years	190 (60)
Male sex	206 (65)
Hemoglobin level, g/dl	10.3 (4-17)
Hemoglobin <11.5 g/dl	226 (72)
Platelet count, K/uL	211 (9-639)
Platelet count <100 K/uL	42 (13)
Serum IgM level, mg/dl	3400 (88*-10 321)
Serum IgM level >4000 mg/dl	129 (40)
Serum IgM level >7000 mg/dl	15 (5)
Serum β2-microglobulin level, mg/l	3.6 (1.4-18.3)
Serum β2-microglobulin level >3 mg/l	164 (65)
Serum albumin level, g/dl	3.7 (2.1-5)
Serum albumin level ≤3.5 g/dl	92 (30)
BM involvement	60 (5-100)
BM involvement ≥60%	154 (55)
IPSSWM
Low	64 (24)
Intermediate	92 (34)
High	112 (42)
MYD88 mutated	265 (97)
CXCR4 mutated	89 (36)
Previously untreated	100 (31)
Previously treated	219 (69)
Median number of prior lines	2 (1-8)
≥2 prior lines	115 (53)

^*Six patients with normal serum IgM levels had an IgM monoclonal spike in the serum protein electrophoresis.