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) × 109/L in chronic patients to 131 (CI 102-160) × 109/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.

AHEPA University Hospital Aristotle University of Thessaloniki Thessaloniki Greece

Algemeen Ziekenhuis Sint Jan Bruge Belgium

Amgen Inc Rotkreuz Switzerland

Amgen Inc Thousand Oaks USA

Amgen Ltd Uxbridge UK

Charles University Prague Czech Republic

Department of Epidemiology University of North Carolina at Chapel Hill Chapel Hill USA

Department of Population Health Sciences Duke University Durham UK

Hospital du Haut Leveque Pessac France

NoviSci Inc 201 W Main St Ste 101 Durham NC 27701 USA

Universitätsklinik für Innere Medizin 5 Innsbruck Innsbruck Austria

University Hospital of Heraklion Heraklion Greece

University Hospitals Leuven Leuven Belgium

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