OBJECTIVETo investigate the clinical and hematological features and identify the prognostic factors associated with short-term survival in primary myelofibrosis (PMF) patients under 45 years old.

METHODSThe clinical manifestations, laboratory parameters, and survival were retrospectively analyzed in 56 PMF patients under 45 years old. Univariate analysis of prognostic factors was performed using Logrank test and multivariate analysis using COX model.

RESULTSOf the 56 patients, 27 were males and 29 females. The range of age was from 20 to 45 years (median 38 years). 84% of the patients were anemic and 66% Hb < 100 g/L. 32% of the patients had constitutional symptoms including fever, night sweats and weight loss. The median survival was 69 months (95% CI 11-127). By univariate analysis, Hb < 100 g/L, platelet count < 100 x 10(9)/L, WBC < 10 x 10(9)/L, constitutional symptoms and the duration from first signs to diagnosis < or = 6 months were associated with poor prognosis. By multivariate analysis, only Hb < 100 g/L and constitutional symptoms were independently associated with short survival. With these two adverse prognostic factors, the patients could be separated into a high risk and a low risk groups, and the median survivals were 16 and 88 months, respectively (P < 0.001). Using these two factors to predict the less than 3-years survival for individual patient, the sensitivity, specificity and positive predictive value were 67%, 100% and 100%, respectively.

CONCLUSIONHb < 100 g/L and constitutional symptoms in PMF patients under 45 years old were significantly associated with short survival and poor prognosis. These two prognostic factors enabled to separate patients into a high and a low risk groups. The survival of high-risk patients was less than three years.