Self-injected SC versus IV Biologic Agents for RA

San Diego—Based on a new claims-based algorithm developed to evaluate the effectiveness of biologics for rheumatoid arthritis (RA), self-injected subcutaneous (SC) first-line biologic agents are more effective than intravenous (IV) administered agents in RA patients.

This is a conclusion of a study presented during a poster session at the AMCP meeting. The poster was titled Comparative Effectiveness of First-Line Subcutaneously versus Intravenously Administered Biologics for Rheumatoid Arthritis Using a Validated Claims Data-Based Algorithm in a Large US Commercial Health Plan.

In the study, investigators used a new claims-based algorithm to compare the effectiveness of commonly used biologic agents approved for first-line treatment for moderate to severe RA among 5474 patients in a large US health insurance plan. The study compared the efficacy between patients treated with self-administered SC agents (adalimumab, etanercept, and golimumab) (n=4406) and those treated with IV agents (abatacept and infliximab) (n=1068).

Patients included in the study had at least 1 claim for a biologic approved agent for RA treatment between January 2007 and December 2010, had continuous enrollment with medical and pharmacy benefits throughout the preindex (6 months preceding the index date) and postindex (12 months after the index date) periods, were 18 to 63 years of age as of the index date, and had at least 1 diagnosis of RA.

Patients with ≥2 claims for biologics on the index date were excluded from the study, as were those with a claim for any biologic agent for RA during the 6-month preindex period, and those with a diagnosis for another indication for which these biologic agents are approved during the preindex and postindex periods.

Overall, sex and geographical region were similar between the 2 groups. Patients in the SC group were slightly younger than those in the IV group (mean age of 48.4 years vs 49.7 years, P<.001), and more patients in the IV group used methotrexate prior to baseline and concomitantly compared with those in the SC group.

To compare the effectiveness of the SC and IV biologic agents, investigators used the definition of effectiveness employed by the algorithm. Under this definition, effectiveness was having none of 6 outcomes during the 12-month postindex period: (1) low adherence; (2) increased biologic dose; (3) biologic switch; (4) new disease-modifying antirheumatic drug (DMARD); (5) use of glucocorticoid; and (6) multiple joint injections.

The study found that SC agents were more effective in a higher percentage of patients than IV agents (30.6% vs 22.1%). Among the 6 outcomes, significant differences between SC and IV agents were seen in low adherence (57.9% vs 39.6%, P<.001), increased biologic dose (7.1% vs 38.6%, P<.001), new DMARD (15.5% vs 12.5%, P=.017), glucocorticoid (12.6% vs 15.4%, P=.012), and multiple joint injections (7.1% vs 9.7%, P=.003).

Based on these results, the investigators recommend that the findings of their study be used in future studies to evaluate the cost effectiveness of these biologic agents or to perform a cost-per-responder analysis.

Limitations of the study included use of claims data that were designed for payment purposes and not for research, the inability to observe the use of biologic therapy more than 6 months before the index date, and the inability to know whether there was any correlation between the length of enrollment and choice of biologic or outcomes as assessed by the algorithm because the study was limited to RA patients with at least 12 months of continuous enrollment after the first prescription for 1 of the biologic agents.

This study was funded by Immunex Corporation, a wholly owned subsidiary of Amgen Inc., and by Wyeth, which was acquired by Pfizer Inc. in October 2009.