Essential thrombocythemia in young adults: major thrombotic complications and complications during pregnancy--a follow-up study in 68 patients.

OBJECTIVES: Although essential thrombocythemia (ET) is usually primarily considered a disorder of middle age, it has been observed in children and young adults. However, the real risk for thrombosis in these patients has not been clearly established.

DESIGN: Prospective analysis of consecutive patients younger than 40 at the time of the diagnosis of ET and followed in our department between 1980 and 1998.

SUBJECTS: Sixty-eight patients (28 males and 40 females, median follow-up 99.14 months) affected by ET diagnosed in agreement with the Polycythemia Vera Study Group criteria.

INTERVENTIONS: Asymptomatic ET patients were not treated. In contrast, patients with associated atherosclerotic risk factors, microvascular disturbances, or a previous major arterial thrombosis were given acetyl salicylic acid (ASA 100 mg/day). Only patients with major thrombotic complications and a platelet count > 1,000 x 10(9)/L received cytoreductive therapy.

OUTCOME MEASURES: (1) to evaluate thrombotic complications in young patients with ET, (2) to relate thrombotic risk to the presence of general atherosclerotic risk factors, and (3) to adopt treatment, and (4) to report the outcome of the pregnancies monitored in our population.

RESULTS: Fifteen patients had major thrombosis, 11 of which were the presenting features of ET. No rethrombosis has been observed. Only one patient with thrombotic complications was under efficient treatment. Atherosclerotic risk factors are more common in patients with major arterial thrombosis than in asymptomatic subjects. Thirteen normal babies were delivered out of 16 pregnancies, 6 of the pregnant women were on ASA therapy.

CONCLUSIONS: Most thrombosis in young ET patients occurred at the time of the diagnosis, and venous thrombotic events represent one-third of total thrombosis. Cardiovascular risk factors seem to be concurrent stimuli for arterial thrombosis in ET. The thrombotic complication rate was 2.6/100 patients/year ASA reduces microvascular disturbances, thrombosis, and rethrombosis and possibly reduces obstetric complications in women with ET.