Objectives The aim of this study was to characterize the treatment patterns of patients with RA treated with biologics and evaluate the direct biologics cost and medical cost using Japanese claims data provided by Japan Medical Data Center Co Ltd.
Methods Patients with RA (defined by ICD10 code: M058, M059, M060, M068, M069), aged ≥16 to <75 treated with etanercept (ETN), infliximab (IFX), adalimumab (ADA), and toclizumab (TCZ) as first biologic, between Jan 2005 and Mar 2013 were included. One-, two- and three-year cumulative total medical cost following initial prescription was compared between each treatment group. Discontinuation event rates in each group were estimated using Kaplan-Meier survival analysis. Dose of each first biologic treatment until discontinuation was analyzed to calculate relative dose intensity (RDI) which shows (Actual cumulative dose)/(Expected dose when initial dose was continued until discontinuation).
Results A total of 603 patients were identified for longitudinal analysis, with 41% (n=246) initiating ETN, 36% (n=217) initiating IFX, 11% (n=69) initiating ADA and 12% (n=71) initiating TCZ. The total medical costs from the initial prescription in ETN, IFX, ADA and TCZ groups were approximately $19,000, $26,000, $23,000 and $24,000 in one year, and $50,000, $65,000, $52,000 and $71,000 in three years, respectively (ETN: IFX p=0.004, ETN: ADA p=0.988, ETN: TCZ p=0.027, ADA: IFX p=0.417, ADA: TCZ p=0.845, IFX: TCZ p=0.198) (Fig 1). The discontinuation event rate at 36th month was 46.4%, 58.0%, 75.8% and 59.3% in ETN, IFX, ADA and TCZ groups, respectively (ETN: IFX p=0.007, ETN: ADA p<0.001, ETN: TCZ p=0.037, ADA: IFX p=0.147, ADA: TCZ p=0.767, IFX: TCZ p=0.385) (Fig 2). The mean RDIs of ETN25mg, ETN50mg, IFX, ADA and TCZ groups were 1.08 (95%CI: 1.00-1.15), 0.89 (95%CI: 0.85-0.93), 1.21 (95%CI: 1.16-1.27), 0.99 (95%CI: 0.92-1.06), and 0.96 (95%CI: 0.84-1.08), respectively (Fig 3).
Conclusions The discontinuation rate was lowest in the ETN group, which indicates sustained treatment and good adherence to the therapy. RDI analysis of IFX showed a 1.21 times higher than expected dose. This high RDI value was due to the dose escalation from initial phase of treatment and may be one of the reasons for the higher cost of IFX observed in our study. These results support the relation between adherence and medical cost reduction in RA patients previously reported.1
Clark et al. The Relationship Between Adherence and Health Care Cost among Patients with Rheumatoid Arthritis: A Retrospective Case Comparison Study. International Society for Pharmacoeconomics and Outcomes Research. 19th Annual International Meeting 2014
Disclosure of Interest N. Sugiyama Employee of: Pfizer, T. Murata Consultant for: Employee of CRECON who performed the analyses and were funded by Pfizer, Employee of: Employee of CRECON who performed the analyses and were funded by Pfizer, Y. Morishima Employee of: Pfizer, Y. Fukuma Employee of: Pfizer, Y. Shibasaki Employee of: Pfizer, L. Marshall Employee of: Pfizer