Clinical Epidemiology (May 2020)
Treatment Patterns Among Adults with Primary Immune Thrombocytopenia Diagnosed in Hematology Clinics in the United States
Abstract
Leah J McGrath,1 Karynsa Kilpatrick,2 Robert A Overman,1 Diane Reams,1 Anjali Sharma,2 Ivy Altomare,3 Jeffrey Wasser,4 M Alan Brookhart1,5 1NoviSci, Inc., Durham, NC, USA; 2Amgen Inc, Thousand Oaks, CA, USA; 3Duke University Medical Center, Durham, NC, USA; 4University of Connecticut, Farmington, CT, USA; 5Department of Population Health Sciences, Duke University, Durham, NC, USACorrespondence: Leah J McGrathNoviSci, Inc, PMB 218, 201 W Main Street, Ste 200, Durham, NC 27701, USATel +1 919 390 1642Email [email protected]: Patients with immune thrombocytopenia (ITP) have low platelet counts and an increased risk of bleeding. We described treatment patterns and clinical outcomes in routine practice in the United States (US).Patients and Methods: Using electronic health record data from hematology/oncology clinics linked to administrative claims in the US, we studied 447 adults newly diagnosed with primary ITP from 2011 to 2016. Patients with a secondary cause of thrombocytopenia were excluded. The incidence of ITP treatment initiation, bleeding events, and rescue therapy use were estimated using competing risk models.Results: At 1-year post-ITP diagnosis, 50% of patients were prescribed an oral corticosteroid, with the majority being prescribed immediately following diagnosis. Of the more common second-line options, rituximab use was the most frequent (1-year cumulative incidence: 16% [95% confidence interval: 12, 19]), followed by romiplostim (9% [7, 12] and eltrombopag (5% [3, 8]). Use of these drugs was similar at 2 years post-diagnosis. At 6 months post-ITP treatment initiation, the cumulative incidence of bleeding was similar among eltrombopag and romiplostim initiators (17% [6, 33] and 19% [9, 31], respectively) and was slightly lower in rituximab users (12% [6, 20]). However, during this same timeframe, rituximab users had a higher incidence of rescue therapy use (48% [36, 58] versus 29% [14, 46] in eltrombopag and 26% [14, 39] in romiplostim users). Although splenectomy was rare, at 6 months post-surgery nearly 20% had experienced a bleed and nearly 20% had required rescue.Conclusion: This study describes the health trajectory of adults with ITP who are managed in hematology clinics in the US and could inform the design of non-interventional studies of comparative effectiveness among treatments.Keywords: primary immune thrombocytopenia, thrombopoietin receptor agonists, rituximab, splenectomy, real-world evidence
