Role of Ethnicity in Clinical Outcomes of Patients with Ph-Negative Myeloproliferative Neoplasms

Abstract 2076

Myeloproliferative neoplasms (MPN) have similar incidence rates across different ethnicities in the United States. However, reported clinical studies rarely address the outcome in patients with different ethnicities. In this study, we retrospectively analyzed 127 patients with a diagnosis of MPN followed at the University of Illinois Hospital between January 2005 and July 2011. Of these patients, 69 were Caucasian and 58 Non-Caucasian (mostly African-American and Hispanic). The median age was 50 years (range: 20–85) in non-Caucasians and 51 years (range: 22–89) in Caucasians. Among 127 patients, 53 had polycythemia vera (PV), 52 essential thrombocythemia (ET), and 22 primary myelofibrosis (PMF). In each disease group, the following parameters were compared at diagnosis between Caucasian and non-Caucasian patients: age/gender, JAK2 V617F mutation status, cytogenetic abnormalities, family history of MPNs, constitutional symptoms, white blood cell (WBC) and platelet count, hemoglobin level, and spleen size. In addition, the two groups were compared for thrombotic or hemorrhagic events, cardiovascular complications, progression of disease, secondary cancer and overall survival. Among 53 PV patients, Caucasians (n=33) had higher WBC counts (11.7 vs. 8.1 ×10³ cells/μL, p=0.03) and a greater spleen size (14 vs. 10 cm longitudinal diameter, p=0.03) at diagnosis compared to non-Caucasians (n=20). However, more frequent hemorrhagic (38.9% vs. 6.1%, p=0.003) and cardiovascular (27.8% vs. 3%, p=0.009) complications were seen in the non-Caucasian cohort of patients compared to the Caucasian cohort. Use of hydroxyurea (55% vs. 57%), aspirin (88% vs. 76%), anagrelide (10% vs. 24%), interferon (18% vs. 5%) and anticoagulation (21% vs. 20%) were not significantly different between Caucasians and non-Caucasians. In the ET patients (non-Caucasian: n=27; Caucasian: n=25), there were no significant differences in presenting characteristics, type of therapies, or clinical outcomes between the two groups. The 22 patients with PMF were classified according to the international prognostic scoring system (IPSS) at diagnosis. In 11 non-Caucasian and 11 Caucasian patients, differences of patients at low risk (18% vs. 9%), intermediate-1 (55% vs. 27%), intermediate-2 (27% vs. 55%), or high risk (9% vs. 0%) were not statistically significant. In a multivariate logistic regression analysis, we demonstrated that prior history of thrombosis and older age are independent prognostic factors for subsequent thrombotic or hemorrhagic events (p=0.03 and p=0.003, respectively). Neither WBC at diagnosis nor ethnicity were independent prognostic indicators in this series of patients. With a median follow-up of eight years (range 1–23 years), median overall survival was not reached for PV, ET, or PMF and no significant differences were detected in Caucasian or non-Caucasian groups. Our observations suggest that when given equal access to care, similar clinical outcomes are achieved in Caucasian and non-Caucasian patients with MPNs.