Aspirin responsive platelet thrombophilia in essential thrombocythemia and polycythemia vera

Table 9 Fatal and non-fatal major thrombosis in 1630 polycythemia vera patients enrolled in the prospective 2004 European Collaboration on Low Dose Aspirin PV studies[90,91]

ECLAP study patient populations	n (%)
Observational study[91]: n = 1112 of which 66% on aspirin
RCT low dose aspirin vs placebo[75]: n = 518 of which 50% on aspirin
Total number of PV patients[90,91]	1630 (100)
On aspirin observational study plus trial	990 (61)
Previous thrombosis	636 (39)
Overall results, follow-up 2.7 yr
Fatal thrombosis	67 (4.1)
Cardiovascular disease	35 (2.9)
Stroke	13 (0.8)
Pulmonary embolism	6 (0.4)
Non-fatal thrombosis	187 (11.4)
Arterial	90 (5.5)
Transient ischemic attacks	33 (2.0)
Stroke	23 (1.4)
Peripheral arterial thrombosis	20 (1.2)
Myocardial infarction	14 (0.9)
Venous	97 (5.9)
Superficial thrombophlebitis	46 (2.8)
Deep vein thrombosis	38 (2.3)
Pulmonary embolism	13 (0.8)
Total fatal and non-fatal thrombosis	254 (15.5)

Data of treated polycythemia vera (PV) patients on aspirin versus not on aspirin are only available for the European Collaboration on Low Dose Aspirin in PV (ECLAP) randomized clinical trial on low dose aspirin vs placebo. PV treatment modalities: 28% phlebotomy only, 26% chemotherapy only, and 35% phlebotomy plus chemotherapy, no phlebotomy and chemotherapy 11% and hydroxyurea was the cytoreductive drug in 79%.