Clinical Characteristics, Prognostic Factors, and Thrombotic and Bleeding Outcomes in Philadelphia Chromosome-Negative Myeloproliferative Neoplasms: A Single-Center Cohort Study in Thailand

Background Patients with Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-neg MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), face elevated risks of thrombosis and major bleeding. Because of these potentially severe complications, antiplatelet and anticoagulant therapies are often employed. This study aimed to evaluate thrombotic and bleeding events, identify associated risk factors, assess prognostic risk models, and investigate the effects of antithrombotic therapy in a Thai cohort of patients with Ph-neg MPNs. Methods This single-center cohort study in Thailand enrolled patients with Ph-neg MPNs from 2013 to 2023. Clinical characteristics, prognostic risk models (International Prognostic Scoring System (IPSS), International Prognostic Score for Essential Thrombocythemia (IPSET)-thrombosis, and Dynamic International Prognostic Scoring System (DIPSS)), and arterial and venous thrombotic events and bleeding complications were analyzed using descriptive statistics, logistic regression, and survival analysis. Results Among 173 patients, PV was the most common subtype (n = 111, 64.2%), with a male predominance and a median age of 57 years. Thrombotic events occurred in 36.9% (n = 41) of PV, 21.4% (n = 3) of PMF, and 18.8% (n = 9) of ET cases, with arterial thrombosis, particularly ischemic stroke, being the most frequent. The <i>JAK2</i> <i>^V617F</i> mutation was prevalent in 72.5% (n = 79) of PV, 70.8% (n = 34) of ET, and 50% (n = 5) of PMF patients. Notably, no major bleeding events were observed despite intensive antithrombotic therapy. Multivariable analysis revealed that prior ischemic stroke (OR 22.51, <i>P </i>= 0.007) and dizziness/headache (OR 7.26, <i>P</i> = 0.022) were significant risk factors for thrombosis. Overall survival (OS) varied by disease subtype. PV patients had a five-year OS of 94.9% and a 10-year OS of 87.2%. ET patients demonstrated a five-year OS of 77.4%. PMF patients had the lowest survival, with a five-year OS of 67.7%. Conclusions This cohort study offers important insights into the clinical characteristics and complication profiles of Ph-neg MPNs in a Thai population. Compared with Western cohorts, patients in this study exhibited a higher incidence of thrombotic events, particularly ischemic stroke. These findings emphasize the need to consider regional variations in disease presentation and underscore the value of individualized risk stratification to optimize patient management in diverse clinical settings.