(233) Real-World Incidence of Selected Clinical Events in Patients Diagnosed with Myelofibrosis

Publication Number: 1224

Background: Background incidence rates (IRs) of selected events potentially associated with JAK inhibitors among patients with myelofibrosis (MF) are needed to further evaluate their safety profile.

Objectives: To estimate the IR and the cumulative incidence function (CIF) of selected events (encephalopathies, renal dysfunction, serious or opportunistic infection, severe liver dysfunction, cardiovascular events, thrombotic events, and subsequent primary malignancy [SPM]) in patients with MF and to assess the association of risk factors with each of these events.

Methods: This was a retrospective cohort study using medical claims data from the IQVIA PharMetrics® Plus and Quest Laboratory databases. The study period was from Jul 2014 to Sep 2021. Patients with at least 1 diagnosis of MF (index date) during the identification period (Jan 2015 - Aug 2021) and ≥6 months pre-index follow-up and ≥1 month post-index follow-up were identified.
IRs per 1,000 person-years and CIFs were calculated for the first post-index occurrence of each of the selected events. Cox proportional hazard ratios were conducted for each event among incident patients while introducing covariates to identify risk factors associated with the development of each of the events.

Results: A total of 2,269 patients met the selection criteria (52% male; median age 60 years). The mean (standard deviation) duration of follow-up was 20.6 (18.9) months. The most frequently prescribed MF treatments were systemic corticosteroids (47.5%), red blood cell transfusions (30.5%), hydroxyurea (19.2%), and ruxolitinib (18.2%). The selected clinical events and their IRs per 1000 person-years and 95% confidence intervals were: invasive SPM (218.5; 199.9-238.4), any renal dysfunction (144.1; 130.1-158.4), serious or opportunistic infections (138.1; 125.6-151.6), cardiovascular events (119.4; 107.1-132.1), thrombotic events (51.5; 44.2-59.5), overall encephalopathy (47.4; 40.1-54.9), and severe liver dysfunction (29.1; 23.8-37.1).
Many of the risk factors identified for the events could be accounted for by physiological mechanisms and established pathogeneses (e.g., peripheral arterial disease, smoking history, cardiac arrhythmias, COPD, diabetes, renal disease, insurance type, and patient age were the significant factors associated with an increase in post-index cardiovascular events).

Conclusions: The leading post-index events observed in MF patients were invasive SPM, renal dysfunction, serious or opportunistic infections, and cardiovascular events. The incidence of the selected events among MF patients appears to be related to non-MF (and non-JAK inhibitor) processes.