PB2211 RESULTS FROM A REAL‐WORLD, RETROSPECTIVE STUDY EVALUATING THE THROMBOEMBOLIC EVENTS AND THE ASSOCIATED RISK FACTORS IN JAPANESE PATIENTS WITH POLYCYTHEMIA VERA
Authors: Komatsu N. , Jun G. , Yonezu T. , Ohashi Y. 
Published: June 2019

Background:

Polycythemia vera (PV) is marked by hyperproliferation of erythroid, myeloid, megakaryocytic components in the bone marrow (clinically manifested as erythrocytosis, leukocytosis, and thrombocytosis) often resulting in thromboembolic events (TEs), cardiovascular complications (CVCs), and poorer prognosis for survival. The treatment of patients (pts) with PV is directed towards maintaining a strict hematocrit of <45% to reduce the risk of TEs and CVCs. Age ≥60 years and history of thrombosis have mainly been associated with the emergence of TEs; additional risk factors like CVCs, leukocytosis, and presence of JAK2 mutation may further enhance the risk of TEs. Only few real‐world studies evaluated the occurrence of TEs in pts with PV in Japan. Here, we report the results from a retrospective study analyzing TEs and the associated risk factors in Japanese pts with PV.

Aims:

To evaluate the incidence of TEs, time to TEs, correlation of risk factors with TEs, and healthcare resource use in Japanese pts with PV.

Methods:

This was a retrospective study of pts with PV diagnosed per International Classification of Diseases (ICD‐10‐CM [C900] codes) during the study period from April 1, 2008 to August 31, 2015 in Japan. The health insurance claims data provided by Medical Data Vision (MDV Co., Ltd., Japan) were utilized for this study. The primary objective was to identify the number of pts with PV who had arterial/venous TE after PV diagnosis (overall incidence rate of TEs). The key secondary objectives included time to TEs, correlation of risk factors with TEs, healthcare resource use, and demographic/baseline pt characteristics. Leukocytosis and JAK mutation were not evaluated as risk factors (owing to study limitation [claims database analysis]).

Results:

Overall, 606 pts with PV were identified. The demographic and baseline pt characteristics of interest were as follows: male/female = 56.9%/43.1%; age (years): median (range) = 67.0 (23‐97; [<60 = 25.7%, ≥60 = 74.3%]); time since PV diagnosis (months), median (range) = 21.770 (0.03‐86.26); risk factors: previous TEs = 11.6% pts, CVCs = 45.7% pts, ≥3 risk factors = 19.0% pts, age ≥60 years and previous TE = 9.9% pts, age ≥60 years or previous TE = 75.9% pts. In total, 200 events were observed in 147 pts (24.3%) at a rate of 13.81/100 person‐years (TE = 16.5%; death = 4.3%; nonhematologic malignancies = 3.3%; bleeding = 3.1%; and disease progression [myelofibrosis/acute myeloid leukemia] = 2.1%). Overall, 100 pts (16.5%) had a TE (118 events) at a rate of 8.15/100 person‐years. The most commonly reported TE was ischemic stroke (10.7%), followed by venous thromboembolism (2.8%), acute myocardial infarction (2.3%), transient cerebral ischemic attack (1.2%), and peripheral arterial thrombosis (0.5%). The correlation between TEs and risk factors (age, history of thrombosis, CVCs, and number of risk factors) are presented in Table (A). The thromboembolic event‐free survival rate was 69.3% (time to TE, Figure [B]). The annual total healthcare costs (mean [per person]) were significantly impacted by the presence of TEs (yes [n = 100] vs no [n = 506]: ¥992536.2 vs ¥459137.6; P<0.001).

Summary/Conclusion:

As reported by other population‐based analyses, results from this real‐world MDV database analysis confirm that age ≥60 years, history of thrombosis, CVCs, and presence of ≥3 risk factors increase the risk of TE occurrence (univariate analysis). This highlights the need for risk‐adaptive therapy for these pts with PV in Japan. The study results are based on hospital‐based claims; hence, warrant careful interpretation and further confirmation in clinical trial/real‐world setting.

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