Effectiveness and Safety of Romiplostim Among Patients with Newly Diagnosed, Persistent and Chronic Immune Thrombocytopenia in European Clinical Practice

Introduction Romiplostim has been approved in Europe since 2009 to treat patients with chronic primary immune thrombocytopenia (ITP). Using real-world data from seven European countries, we measured the effectiveness and safety outcomes within 24 weeks following romiplostim initiation by duration of ITP: less than 3 months ("newly diagnosed"), 3-12 months ("persistent"), and more than 12 months ("chronic"). Methods Adults with ITP and >= 1 romiplostim administration between 2009 and 2012 were included. Endpoints included durable platelet response, median platelet count, rescue therapy, bleeding and adverse events. We used inverse probability of censoring weighted estimators to estimate cumulative risk of each outcome. There were 64 newly diagnosed, 50 persistent, and 226 chronic ITP patients at romiplostim initiation. Results Durable platelet response at 24 weeks ranged from 32% [confidence interval (CI): 18-46%] in newly diagnosed patients to 53% (CI 37-68%) in persistent patients. Median platelet count during follow-up ranged from 88 (CI 80-96) x 10(9)/L in chronic patients to 131 (CI 102-160) x 10(9)/L in newly diagnosed patients. Conclusion Regardless of ITP duration, over half of patients discontinued concomitant ITP medications. Few adverse events were observed. Although only approved for chronic patients, estimates of the romiplostim treatment effect were similar across patients being managed in European clinical practice, regardless of ITP duration at romiplostim initiation.