Effect of availability of oral iron chelation therapy (ICT) on initiation, duration, and dose adequacy in patients with myelodysplastic syndromes (MDS) and transfusional iron overload (TIO).

Abstract

e17584 Background: Most patients with MDS do not receive ICT despite evidence of TIO. Till 2005, the only approved ICT was Deferoxamine (DFO), a drug which requires daily prolonged parenteral administration. In addition to therapeutic equipoise of its efficacy, the logistics of administration of DFO may limit ICT use in MDS. We sought to assess whether the approval of an oral ICT (Deferasirox, DFX) in November 2005 has changed ICT use rates, dose adequacy and adherence in MDS patients with TIO. Methods: Using 100% Medicare enrollment and claims data from 2005-2008, we selected beneficiaries with MDS who were enrolled in Medicare Parts A, B, and D and were ICT-eligible based on RBC transfusions ≥ 20 units. Cox proportional hazard models examined the effect of time period relative to DFX market entry on the probability of ICT initiation and the effect of DFX vs. DFO use on duration and dose adequacy. Results: Of 3,843 ICT-eligible patients, 13.8% received ICT, with 81.6% of those receiving DFX, and 29.5% receiving DFO. Relative to the latter half of 2005, the probability of ICT initiation increased beginning in 2007, with a hazard ratio of 1.793 (CI,1.13-2.84; P=0.012) associated with cohort entry in the latter half of 2008. Treatment duration was longer for beneficiaries using DFX (mean 29.7, median 22 weeks) compared to DFO (mean 19.43, median 9 weeks). Only 7.1% of DFO-users received an adequate dose, compared to 72.8% of DFX-users. Conclusions: Use of oral ICT (DFX), following its approval, was associated with increased use, duration and dose adequacy of ICT, compared to DFO, among Medicare beneficiaries with MDS and TIO. The dramatic increase in use associated with availability of an oral formulation may have implications for other new oral chemotherapy and supportive care drugs.