Background: Several anti-inflammatory biologic medications are available in the United States for the treatment of moderate-to-severe rheumatoid arthritis, moderate-to-severe psoriasis, psoriatic arthritis, or ankylosing spondylitis. The tumor necrosis factor (TNF) blockers etanercept, adalimumab, and infliximab are approved for use in adults with any of these conditions, but predicting the annual costs of TNF-blocker treatment is complex due to differences in dosing schedules, treatment gaps, switching between TNF blockers, and dose escalation over time.
Objectives: To estimate the annual cost per treated patient from the payer perspective for etanercept, adalimumab, or infliximab in adults with rheumatoid arthritis, psoriasis, psoriatic arthritis, or ankylosing spondylitis.
Methods: Adults in the IMS LifeLink Health Plan Claims Database were analyzed if they had at least 1 claim for etanercept, adalimumab, or infliximab between February 1, 2008, and July 5, 2010, and were continuously enrolled for at least 180 days before (pre-index period) through 360 days after the index claim (the first TNF-blocker claim after 6 months of continuous enrollment in the study period). Patients had a diagnosis of rheumatoid arthritis, psoriasis, psoriatic arthritis, or ankylosing spondylitis, or a combination of these conditions, in the pre-index period. Cost was based on dose and price using April 2012 wholesale acquisition cost. Costs of administration were included for the first subcutaneous dose (etanercept or adalimumab) for new patients and for every intravenous dose (infliximab). Total TNF-blocker drug and administration costs, including nonindex TNF-blocker costs among patients who switched treatments, were divided by number of patients to yield cost per treated patient for each index TNF blocker. Subgroup analyses included cost by condition and cost for patients who were new to TNF-blocker treatment (no index TNF-blocker claim in the pre-index period) or continuing TNF-blocker treatment.
Results: Of the 30,107 patients in the analysis, the majority received etanercept (15,488 patients; 51.4%), followed by adalimumab (8,959 patients; 29.8%) and infliximab (5,660 patients; 18.8%). Approximately 2 in 3 patients (18,897 patients) were continuing TNF-blocker treatment, including 66.0%, 52.6%, and 70.0% of patients in the etanercept, adalimumab, and infliximab groups, respectively. Across all indications, the annual TNF-blocker cost per treated patient was lowest for etanercept, followed by adalimumab and then infliximab, respectively: overall ($17,767, $19,272, and $24,273); new patients ($17,270, $17,959, and $21,482); and continuing patients ($18,203, $20,453, and $25,468). Cost by condition among all patients ranged from $14,838 to $20,251 for etanercept, from $18,051 to $20,233 for adalimumab, and from $22,939 to $28,519 for infliximab. Cost by condition was 3% to 31% greater for adalimumab than for etanercept (relative cost, 103% to 131%), except among patients with psoriasis (relative cost, 94%), and was 26% to 72% greater for infliximab than for etanercept (relative cost, 126% to 172%). Approximately 9% to 11% of patients in each group switched TNF blockers in the first year, and the costs of nonindex TNF blockers comprised 16.8% of the total cost for etanercept, 13.4% for adalimumab, and 6.9% for infliximab.
Conclusions: In adult patients with rheumatoid arthritis, psoriasis, psoriatic arthritis, or ankylosing spondylitis, or some combination of these conditions, etanercept had a lower cost per treated patient than adalimumab or infliximab, except in patients with psoriasis alone. In these patients, adalimumab had a lower cost per treated patient than etanercept or infliximab.