Published in:
Open Access 01-12-2011 | Research article
Patterns of biologic agent utilization among patients with rheumatoid arthritis: a retrospective cohort study
Published in: BMC Musculoskeletal Disorders | Issue 1/2011
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Background
The role of biologic therapies in the treatment of rheumatoid arthritis has expanded, but dosing patterns in the first versus subsequent lines of therapy have not been thoroughly explored.
Methods
In order to describe patterns of biologic agent utilization among patients with rheumatoid arthritis, health care claims data on use of abatacept, rituximab, or the anti-tumor necrosis factor (TNF) agents etanercept, adalimumab, and infliximab in first- or subsequent-line settings were used to form patient cohorts. Variables included: starting dose (first administration or fill), maintenance dose (third administration or fill), average dose, dose escalation, inter-infusion interval, and discontinuation (gap in therapy > 60 days or switch). Time to discontinuation was assessed with Kaplan-Meier curves and Cox proportional hazards models.
Results
Over 1 year, average (SD) doses of first-line etanercept (N = 1593; 45.4 [8.8] mg/week), adalimumab (N = 1040; 40.7 [10.4] mg/2 weeks), and abatacept (N = 360; 715.4 [214.5] mg/4 weeks) were similar to the starting and maintenance doses; the average infliximab dose (N = 538; 441.0 [209.2] mg/8 weeks) was greater than the starting and maintenance doses. Trends in the subsequent-line anti-TNF cohorts were similar. The percentages with a dose escalation or discontinuation were greater in the subsequent-line anti-TNF cohorts. The proportion with a dose escalation was greatest for the infliximab cohorts (61.2% first-line and 80.2% subsequent-line). The average period between abatacept infusions was 4.8 [1.4] weeks (4-week approved schedule); and 6.8 [2.6] months between rituximab courses (currently approved schedule is 6 months). Time to discontinuation was significantly shorter for subsequent-line than first-line anti-TNF therapy (median 9.7 vs. 12.5 mo; p < 0.001). The hazard ratio for discontinuing subsequent-line versus first-line anti-TNF therapy was 1.177 (p < 0.001).
Conclusions
Subsequent-line anti-TNF therapy cohorts had higher rates of discontinuation, dose escalation, and shorter time to discontinuation than first-line anti-TNF cohorts.