Aspirin responsive platelet thrombophilia in essential thrombocythemia and polycythemia vera

Table 6 Low, intermediate and high thrombohemorrhagic risk stratification of essential thrombocythemia patients and a flexible approach towards therapeutic implications with reference to platelet counts including essential thrombocythemia patients with features of early polycythemia vera in blood and bone marrow (prodromal polycythemia vera)

Platelets (400-1500 × 109/L)	Platelets (400-1000 × 109/L)	Platelets (400-1000 × 109/L)	Platelets (> 1500 × 109/L)
Low risk	Low risk	High risk	High risk
Completely asymptomatic	Microvascular disturbances only1	Major thrombosis, and/or bleeding	> 1000 × 109/L and minor thrombosis/bleeding = high
No vascular risk	No vascular risk	Vascular risk	No vascular risk
No bleeding risk	No bleeding risk
Age < 65 yr2	Age < 65 yr except2	Age > 65 yr except3	All ages
Aspirin uncertain	Low dose aspirin	Platelet reduction to normal or near normal	Platelet reduction to < 1000 × 109/L
Wait and see?	50 to 100 mg/d
	Intermediate risk
Aspirin primary prevention?	Microvascular disturbances and platelet count between 1000 and 1500 × 109/L with clear indication aspirin1, →side effects (platelet reduction)	Continue aspirin1	When platelets < 1000 × 109/L add aspirin
ET patients and their physician usually prefer the use of low dose aspirin

¹At platelet counts in excess of 1000 × 10⁹/L, aspirin will usually elicit bleeding symptoms, which disappear after reduction of platelet counts to below 1000 × 10⁹/L with continuation of aspirin (Figure 6). If side effects of aspirin (gastritis, gastrointestinal bleeding) occur, reduce platelets to normal and consider indomethacine 25 mg/bid;

²Age over 65 plus one of the following: platelets > 1000 × 10⁹/L or the presence of a vascular risk factor, but otherwise asymptomatic while on aspirin seems to be a clear indication to reduce platelet count;

³Age over 65, platelets < 1000 × 10⁹/L, absence of vascular risk and asymptomatic while on low dose aspirin seems to be no clear indication to reduce platelet to normal (Figure 6).