Costs, Persistence, and Hospitalizations Associated with the Use of Iron-Chelating Therapies in Sickle Cell Disease in Medicaid Patients
Authors: Armstrong Edward P , Skrepnek Grant H , Ballas Samir K. , Kwok Peter , Snodgrass Susan , Sasane Medha 
Published: October 2019

Abstract
Abstract 3152

Objective:
Patients with Sickle Cell Disease (SCD) receiving chronic blood transfusions require iron chelation therapies (ICTs) and good adherence to ICT to avoid sequellae of iron overload. This study evaluated cost, persistence, and medication adherence to ICTs based on a nationwide sample of Medicaid recipients with SCD.

Methods:
This retrospective cohort study evaluated healthcare claims from 2006 to 2010 captured within the Thomson Reuters 10 states Medicaid MarketScan database. Patients with ≥ 1 SCD diagnosis code (282.6x), ≥ 2 claims for ICT medications (deferoxamine (DFO), deferosirox (DFX)), continuously enrolled for ≥ 6 months prior to ICT initiation through 365 days post initiation of ICT were included. ICT utilization was obtained using NDC codes and HCPCS codes. Patients were classified into 3 groups based on their ICT use: DFO only, DFX only, and switches from DFO to DFX. Outcomes evaluated included adherence and persistence to ICT, frequency of SCD crises related hospitalizations, and overall costs. ICT adherence was evaluated using medication possession ratio (MPR) and persistence was defined as medication refill gap of ≥ 6 weeks. Multivariate linear, logistic, and Cox regression analyses were performed after controlling for demographics, number of transfusions, capitated Medicaid coverage, pre-index cost (6months prior to ICT initiation), number of hospitalizations, adherence, and risk-adjusted case-mix comorbidity.

Results:
A total of 484 SCD patients receiving ICTs from 2006 to 2010 within the 10 states were identified. The average age was 18.9 ±11.2 years of age, 45% (n =218) were male, and 64.7% (n=313) were African American. A total of 25.4% (n =123) patients, switched from DFO to DFX while 1.7% (n = 8) switched from DFX to DFO during one-year post-ICT initiation. Patients receiving DFX only, DFO only, or both ICTs received an average of 2.68 (±3.2), 3.54 (±3.0), 3.59 (±3.2) transfusions during the study period, respectively. Compared to pre-ICT period, the number of transfusion claims increased in all three cohorts during the study period; the mean difference was 2.7 in DFO, 3.3 in DFX, and 4.1 in the both ICT group. The Cox regression assessing long-term medication persistency indicated a 1.37 times higher likelihood of treatment discontinuation with DFO compared to DFX. Overall MPR was low in both groups; following one year of treatment, 37.4% remained on DFX compared to 15.7% on DFO (Figure 1). No differences were observed in total healthcare costs, number of hospitalizations and associated costs for SCD-related crises between the DFX only and DFO only cohorts. Meaningful differences in treatment discontinuation between the two treatment groups did not occur until 220+ days during the study period (Figure 1). Thus, a one year timeframe may be inadequate to observe complete impact of ICT adherence on sequellae of iron overload and subsequent resource use. Lengthening the study period beyond one year may be necessary to fully capture the long term impact of adherence on outcomes related to iron overload.

Conclusion:
This study indicated that there were more switches from DFO to DFX, higher medication persistency rate with DFX than DFO, and similar total healthcare costs, numbers of SCD crisis-related hospitalizations, and SCD crisis-related costs between DFO & DFX cohorts. Treatment discontinuation was generally high for all groups, especially for those on DFO, with a one year discontinuation rate of approximately 85%. Future research using a longer observation period than one year will be necessary to assess effects on long term clinical outcomes, resource use, and healthcare costs between different ICTs.
Kaplan-Meier Graph for Treatment Discontinuation Between Deferoxamine and Deferasirox

Disclosures:
Armstrong: Novartis Pharmaceutical Corporation: Consultancy, Research Funding. Skrepnek:Novartis Pharmaceutical Corporation: Consultancy, Research Funding. Ballas:Novartis Pharmaceutical Corporation: Consultancy. Kwok:Novartis Pharmaceutical Corporation: Employment. Snodgrass:Novartis Pharmceutical Corporation: Employment. Sasane:Novartis Pharmaceutical Corporation: Employment.