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)
| Treatment strategy | 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 | ||
1
Mean platelet count 610, range 410-831 × 109/L at time of thrombotic event;
2
Platelet count 624 ± 255 × 109/L at time of thrombotic event;
3
Platelet 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.