Evaluation of survival risk scores in primary myelofibrosis: A Brazilian experience from a single institution

Primary myelofibrosis (PM) is a rare chronic myeloproliferative disorder with a variable prognosis [1]. The etiology is not completely understood yet, but it is possible to demonstrate a monoclonal proliferation of the pluripotent hematopoietic progenitor stem cell by molecular analysis, with the fibrosis being a secondary phenomenon [2,3]. To correctly estimate the survival of PM patients, some clinical–hematological scores were proposed, such as the Dupriez [4] and Cervantes [5,6] scores. The aim of this letter is to describe the clinical and demographic characteristics of a group of PM Brazilian patients at diagnosis by the Dupriez and Cervantes scores and analyze their long term outcome. All consecutive patients with chronic myeloproliferative disease that fulfilled the Polycythemia Vera Study Group diagnostic criteria for PM were eligible for this retrospective analysis. All patients were treated in the Division of Hematology of the São Paulo University Clinics Hospital from July 1992 to June 2007. For the establishment of PM diagnosis by PVSG criteria the following investigations were done in all patients: physical examination, complete blood cell count, bone marrow trephine biopsy, bone marrow cytogenetic study and molecular Bcr-Abl detection. None of the patients had previous diagnosis of other myeloproliferative diseases like polycythemia vera or essential thrombocythemia. The following variables at diagnosis were evaluated: age, gender, presence of splenomegaly, history of previous thrombosis, constitutional symptoms (fever, night sweats and weight loss), hemoglobin concentration (Hb), platelet count, white blood cell count, the presence of leukoerythroblastic picture and teardrop red blood cells, megakaryopoiesis with maturation defects, marrow collagen fibrosis, myeloid metaplasia and cytogenetic aberrations in the marrow. Serum erythropoietin levels were also evaluated, when available. The prognostic scores of Dupriez and Cervantes were determined for each patient. Overall survival (OS) was defined as the time elapsed from the diagnosis of PM to death by any cause or to loss of follow-up. The survival analysis was estimated by the Kaplan-Meier method and compared by the log-rank test. Incidence of secondary acute myeloid leukemia (sAML) was calculated. The diagnosis of sAML was defined according to WHO criteria by the presence of at least 20% blasts at bone marrow or peripheral blood smears. All p values were 2-tailed and alpha error was defined as 5%. The statistical analyses were performed using SPSS 10.0 for Windows (SPSS, Chicago, IL). Forty patients with PM were identified (Table I). The median age of the patients at diagnosis was 62 years old; 13 (32%) had less than 55 years old. Seventeen (42%) patients were female. The median Hb value at diagnosis was 9.7 mg/dL (range: 4.3– 15.1 mg/dL). The median leukocyte count and platelet count were 16 350/mm and 244 000/mm, respectively. All patients had splenomegaly at time of diagnosis. The presence of constitutional symptoms occurred in 60% of the cases. Five (8%) patients had a previous history of thrombotic events (two arterial thromboses and three venous thromboses). The