Table 1.
Clinical characteristics of the 289 PV patients
| Male/female – n (%) | 119/170 (41.2/58.8) |
| Median age at PV diagnosis, years (range) | 52.1 (11.0–84.4) |
| - < 40 years, n (%) | 59 (20.4) |
| - 40–60 years, n (%) | 151 (52.2) |
| - > 60 years, n (%) | 79 (27.4) |
| “PV survival score”a at diagnosis, n (%) | |
| - High risk | 59 (20.4) |
| - Intermediate risk | 84 (29.1) |
| - Low risk | 146 (50.5) |
| Median follow-up time, months (range) | 97.0 (1.0–395.0) |
| Median treatment time on cytoreductive therapyb, months (range) | 73.5 (1.0–311.0) |
| Median treatment time on HUc, months (range) | 45.2 (0.2–289.0) |
| Median treatment time on RUXd, months (range) | 48.0 (1.0–101.6) |
| Median treatment time of cytoreductive therapye except HU/RUX, months (range) | 38.0 (1.0–275.0) |
| Number of patients receiving HUc, n (%) | 185 (64.0) |
| Number of patients receiving RUXd, n (%) | 95 (32.9) |
| Number of patients receiving cytoreductive therapye except HU/RUX, n (%) | 67 (23.2) |
| Patients with a transformation to secondary myelofibrosis, n (%) | 46 (15.9) |
| Patients with a transformation to acute leukemia, n (%) | 6 (2.1) |
a) “PV survival score” [18]: age at first diagnosis (≥ 67 years = 5 points; 55–67 years = 2 points), leukocyte count at diagnosis (≥ 15 × 109/l = 1 point) and venous thrombosis before or at diagnosis (1 point): low-risk (0 points), intermediate-risk (1 or 2 points), and high-risk (≥ 3 points)
b) ASA/phlebotomies were not defined as “cytoreductive therapy”. All patients received phlebotomies and/or low-dose ASA according to “DGHO”-guidelines [17]
c) HU hydroxyurea
d) RUX ruxolitinib
e) Cytoreductive therapy except HU or RUX: interferon alpha n = 40, anagrelide n = 2 1, or busulfan n = 6, respectively