Myeloproliferative and thrombotic burden and treatment outcome of thrombocythemia and polycythemia patients

Table 3 Incidence of thrombotic and bleeding complications in the prospective 1975-1996 Rotterdam study of 68 ET patients during a median follow-up of 6.7 years according to treatment strategy (Van Genderen et al[4,5] 1997)

Treatmentstrategy	Duration of follow-up person (yr)	Thrombotic events		Bleeding events
		Events (n)	Events/100 person (yr)	Events (n)	Events/100 person (yr)
Asymptomatic 14 patients
Watchful waiting	127	271	33.3	2	1.6
Symptomatic 54 patients
Low-dose aspirin	139	5	3.6	103	7.2
Platelet reduction	113	102	8.9	2	1.8
Low-dose aspirin + platelet reduction	40	0	-	4	10
Total	419	42		18

¹Mean platelet count 610, range 410-831 × 10⁹/L at time of thrombotic event;

²Platelet count 624 ± 255 × 10⁹/L at time of thrombotic event;

³Platelet count 1737, range 661-3460 × 10⁹/L at time of bleeding event. These observations by Van Genderen et al[4,5] confirm the concept in Figure 1 on the relationship between platelet-mediated microvascular thrombosis in thrombocythemia at platelet counts between 350 to 1000 × 10⁹/L in ETT and mucocutaneous bleedings at platelet counts of 1000 to above 2000 × 10⁹/L in HT patients.