Utilization Patterns of Infliximab for RA

San Diego—An understanding of the current usage patterns of infliximab in the treatment of rheumatoid arthritis (RA) is a crucial component in the management of patients. Because real-world data of weight-based utilization patterns of this medication is limited, researchers examined the weight-based dosing and utilization patterns in infliximab-treated RA patients in a California ambulatory care network.

Patients with RA were maintained on the medication for an average of 2.3 years during the 4.5-year observation period, according to results presented during a poster session at the AMCP meeting. The poster was titled Utilization of Infliximab for the Treatment of Rheumatoid Arthritis in an Ambulatory Care Network in Northern California.

Patients with a diagnosis of RA (n=125) were retrospectively identified in the electronic health record of Sutter Health’s ambulatory care network between January 1, 2007, and June 30, 2011. Patients ≥18 years of age with ≥1 infliximab infusion were included in the analysis, which was comprised of both incident and prevalent users.

For incident infliximab users, the maintenance dosing phase was defined as the first infusion after the last loading dose. For prevalent infliximab users, the maintenance dosing phase was defined as the first infusion during the study period. The index date was defined (baseline) as the first infliximab infusion occurring during the study period. Patients could have received an infliximab dose before the index date. Patients receiving another biologic agent within 30 days of an infliximab infusion were excluded.

On average, patients were 60 years of age and the majority were female (82%). Medicare beneficiaries were, on average, older than commercial beneficiaries (68.6 vs 51.3 years, respectively) and a smaller percentage of Medicare beneficiaries (9.1%) had received prior biologic therapy compared with commercial beneficiaries (36.4%). Concomitant methotrexate use was documented in 65% of the overall RA infliximab population and was higher with Medicare than commercial beneficiaries (65.2% vs 61.8%, respectively).

Among all patients, the results found that infliximab was administered over a mean of 27.4 months at an average infused dose of 347.2 mg (range 100-875 mg), corresponding to an average weight-based dose of 4.8 mg/kg (range 2.5-11.7 mg/kg). In a subset of 43 patients who were new infliximab users during the study period, the average weight-based dose was 43 mg/kg (range 2.5-9.1 mg/kg). The majority of patients (58%) received an infliximab dose that ranged from
>3 mg/kg to ≤5 mg/kg throughout the study duration.

For the number of infusions, the study showed that 2608 infliximab infusions were administered to the 125 RA patients. In the overall RA population, as well as the commercial and Medicare subgroups, a median of 3 infliximab vials were used per infusion with a median infusion frequency every 8 weeks. Further, the interval frequency increases or decreases occurred in <2% of consecutive infusions. The investigators also found that the mean weight-based dose for the study population increased from 4.5 mg/kg at the index dose to 5.0 mg/kg at the last observed dose in the study period.

This study was supported by Janssen Scientific Affairs, LLC.