Background Tumour necrosis factor inhibitors (TNFi's) such as etanercept (ETN), adalimumab (ADA) and infliximab (IFX) have led to dramatic improvements in the treatment of rheumatoid arthritis (RA), but their impact on medical expenditures remains a concern. It is therefore important to aim for sustained clinical benefits through persistent treatment whilst minimizing the impact of the drug cost on medical expenditures based on initiating the most cost-effective RA treatment.
Objectives The aim of this study is to evaluate retention rates across three commonly used TNFi's and compare associated cumulative direct biologics and medical costs using a nationwide Japanese claims database containing about two million subscribers from the health insurance society provided by the Japan Medical Data Center Co., Ltd.
Methods Subjects of this study were patients with rheumatoid arthritis (ICD10 code: M058, M059, M060, M068, M069) prescribed ETN, IFX or ADA as the first biologics between January 2005 and March 2013. Annual average costs of the initial biologics per patient were calculated between 2005 and 2012. Next, the retention rates of ETN, IFX and ADA were examined using Kaplan-Meier survival analysis. Lastly, the cumulative biologics cost including second (or subsequent) biologics (tocilizumab, abatacept, golimumab, certolizumab and three TNFi's) as well as the total medical costs were compared in the year following the initial prescription of ETN, IFX or ADA (The approved dose in Japan for ETN: 10 to 25 mg twice weekly or 25 to 50 mg per week, IFX: 3 to 10mg/kg every 4 to 8 weeks, ADA: 40 to 80mg every 2 weeks).
Results 524 RA patients initiating selected biologic therapy were identified for this analysis. 238, 217 and 69 patients were prescribed ETN, IFX, ADA as the first biologic, respectively. The annual cost for ETN per patient was about $10,000 in 2007 and $7,200 in 2012. The annual cost for IFX per patient was about $13,000 in 2007, but after approval of dose escalation in 2009, it was $16,000 in 2012. The retention rate of each TNFi at 36 months was 51.4%, 42.0% and 24.2% for ETN, IFX and ADA, respectively (ETN vs. IFX, p=0.053; ETN vs.ADA, p=0.004, Log-rank test) (Fig.1). The average cumulative annual cost of biologics for patients initiated with ETN, IFX and ADA as the first biologics treatment was about $12,000, $18,000 and $16,000, respectively (ETNvs IFX, p<0.001; ETN vs. ADA, p<0.001, IFX vs. ADA, p=0.751, Steel-Dwass test) (Fig.2). The average total annual medical cost with ETN, IFX and ADA as the first biologics treatment were $19,000, $26,000 and $23,000, respectively (ETN vs IFX, p<0.001, ETN vs. ADA, p<0.001, IFX vs. ADA, p=0.826, Steel-Dwass test).
Conclusions The retention rate of ETN as the first biologics treatment was the highest among three TNFi's while cumulative annual cost of biologics and total medical cost following the initial treatment of patients with ETN was significantly lower than comparators. Therefore, ETN may be considered a more cost-effective option to other TNFi's although further research comparing clinical outcomes is warranted.
Disclosure of Interest N. Sugiyama M.D.,Ph.D. Employee of: Pfizer, T. Murata M.S. Consultant for: Pfizer, Y. Morishima Employee of: Pfizer, Y. Fukuma Employee of: Pfizer, Y. Shibasaki M.S. Employee of: Pfizer, C. Bidad M.Pharm. Employee of: Pfizer, J. Harnett Pharm.D.,M.S. Employee of: Pfizer, L. Marshall Employee of: Pfizer, J. Coindreau M.D. Employee of: Pfizer