Thrombosis-free survival and life expectancy in 187 consecutive patients with essential thrombocythemia

A total of 187 consecutive patients with essential thrombocythemia (ET) wer e diagnosed and followed by our Hematology Department in the period October 1980-November 1994. The overall follow-up was 773 patient-years. Thrombosi s-free survival and overall survival were calculated for the whole cohort; the same parameters were then calculated after arbitrary division of the co hort into two groups, according to the median age at diagnosis (55 years). Fifty percent of the patients had at least one thrombotic episode within 9 years after diagnosis. The thrombosis-free survival curves calculated for p atients younger or older than 55 years at diagnosis were comparable. About 85% of the patients were alive 10 years after diagnosis. The survival curve s for :patients younger and older than 55 years at diagnosis were not signi ficantly different in the observation period, and the observed mortality (s even patients) among patients younger than 55 years at diagnosis was signif icantly higher than expected (1.68 cases). The relative risk of death was f our times greater (SMR = 4.17, 95% C.I. 1.6-8.6, p < 0.01) than for healthy , age-matched people living in the same area. Age at diagnosis, smoking, se x, hypercholesterolemia, peak number of platelets, hypertension, and diabet es were not significant prognostic cardiovascular risk factors in our cohor t. In conclusion, our data show that ET has to be considered a serious dise ase that significantly decreases both quality of life (expected life withou t thrombosis) and life expectancy for younger patients.