Background/Purpose: Evaluating the real world effectiveness of biologic DMARDs in rheumatoid arthritis (RA) patients using administrative claims data has previously not been feasible due to the lack of clinical information present in such databases. A novel, recently published, validated administrative data-based algorithm (Curtis et. al., Arthritis Res Ther 2011) provides the potential to compare the effectiveness of different biologics to one another, with focus on older and vulnerable populations that are sometimes excluded or not present in large numbers in clinical trials or registries.

Methods: We evaluated the effectiveness of etanercept, adalimumab, and infliximab in 100% of Medicare beneficiaries with RA and with >= 24 months of fee-for-service + drug coverage, 2006-2009. Patients included those eligible for Medicare on the basis of age >= 65 or disability. New users of anti-TNF agents had a 12 month baseline during which no prescription or infusion of any biologic medication was given. The outcome was effectiveness at 12 +- 2 months according to the algorithm, which required six dichotomous conditions be met (Table).  We calculated the proportion meeting effectiveness criteria by anti-TNF medication and compared effectiveness between them using robust Poisson regression to compute risk ratios (RRs), adjusted for demographics, income, comorbidities and other medications.

Results: We identified 1,635, 2,077 and 3,181 new users of adalimumab, etanercept and infliximab, respectively. Overall, 35% of patients were disabled, almost all of whom were younger than age 65. The algorithm classified the medication as effective for 27% of adalimumab users, 31% of etanercept users, and 29% of infliximab users. After multivariable adjustment, the RRs for effectiveness were 0.99 (95% confidence interval (CI): 0.90-1.10) for adalimumab, and 1.11 (95% CI: 1.02-1.22) for etanercept compared to infliximab. Across all anti-TNFs, patients who were not disabled had higher effectiveness for anti-TNF medications than patients who were disabled (RR=1.26, 95% CI: 1.15-1.39).  

Conclusion:

A recently-published claims-based effectiveness algorithm provides opportunities to assess the comparative effectiveness of RA medications using administrative data.  Etanercept was associated with somewhat higher effectiveness among new anti-TNF users compared to infliximab. Effectiveness of all anti-TNF medications combined was significantly higher among older patients who were not disabled compared to younger, disabled RA patients.

Table: Components of the effectiveness algorithm† for adalimumab, etanercept, and infliximab at 1 year *
	Adalimumab  %	Etanercept %	Infliximab %
Effectiveness Criteria, %
High adherence to the index drug	55	59	65
No switch to a different biologic	87	85	89
No addition of a new non-biologic DMARD	90	90	91
No biologic dose increase compared to starting dose	94	99	84
For patients not using glucocorticoids at baseline, no initiation of glucocorticoids; for patients using glucocorticoids at baseline, no increase in dose	84	88	84
No more than one joint injection on unique days after the 3 months of new treatments	89	90	88
Satisfied all 6 effectiveness criteria	27	31	29
†The gold standard outcome was low disease activity (Disease Activity Score using 28 joint counts (DAS28) <= 3.2) or improvement in DAS28 by >1.2 units at 12+2 months with high adherence to therapy. This newly published claims-based effectiveness algorithm was validated using the clinical information in Veterans affairs RA registry as the gold standard. *assessed between the first exposure date and the outcome rheumatologist visit date (10-14 months later)

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-comparative-effectiveness-of-anti-tnf-medications-among-older-and-disabled-rheumatoid-arthritis-patients-in-the-u-s-medicare-population/