Background/Purpose:

The pharmacologic management of JIA has changed dramatically with the advent of tumor necrosis factor inhibitors (TNFi), but the impact of TNFi on medication usage in routine clinical practice has not been well-studied. Using national administrative claims from a large commercial U.S. health insurer, we investigated the use of medications in the treatment of JIA over the last 8 years. We examined medication use by calendar year, as well as medication use before and after new TNFi use among individual patients.

Methods:

Using data from January 2005 through September 2012, we identified children <17 years old with > 1 physician diagnosis code consistent with JIA.  In the analyses of medication use by year, only subjects with full medical and pharmacy benefits for the entire enrollment period of the calendar year were included.  Use of TNFi, methotrexate (MTX), non-steroidal anti-inflammatory drugs (NSAID), and oral glucocorticoids (GC) was determined using pharmacy and infusion claims. Significant changes in medication usage over time were evaluated with the Cochran-Armitage test for trend.  New TNFi users were defined by no receipt of any TNFi in the 6 months immediately prior to starting. New TNFi users were required to have a minimum of 6 months of follow-up after starting TNFi, and only the earliest episode of new TNFi use for each patient was included. Among prevalent users of NSAID and GC, we used paired t-tests to compare the number of filled prescriptions for NSAID and the cumulative mean daily GC dose (in prednisone equivalents) in the 6 months before and after new TNFi use.

Results:

Including all years of the study, we identified 4,261 individuals with ≥1 JIA diagnosis code.  Their median age was 11 years (IQR 7-14) and 64% were female.  The proportion of TNFi users increased during the study period from 8.7% in 2005 to 22.3% in 2012 (p<0.0001).  Over the same time period, the proportion of MTX users increased from 18.4% to 23.2% (p=0.02), the proportion of NSAID users decreased from 49% to 40% (p=0.02), and the proportion of GC users was relatively unchanged (19.8% to 16.1%; p=0.4). We identified 344 new users of TNFi (70% etanercept, 19% adalimumab, 10% infliximab). Among 194 prevalent NSAID users, the number of NSAID prescriptions decreased in the 6 months following new TNFi use (mean 2.8 prescriptions before versus 2.0 after; p<0.0001).  Among 126 prevalent GC users, the cumulative mean daily dose was significantly reduced in the 6 months following new TNFi use (mean decrease 3.4 mg/day; p<0.0001). Many new TNFi users (195/344, 57%) had not filled a prescription for MTX in the previous 6 months. Of these without recent MTX use, only 11% (21/195) used MTX in the 6 months following new TNFi use. Overall, 38% (129/344) had any concurrent MTX use in the 6 months following new TNFi use.

Conclusion:

TNFi use in the treatment of JIA increased 2-3 fold over the last 8 years with a concurrent smaller increase in MTX use. New use of TNFi was associated with a reduction in the number of NSAID prescriptions and mean daily GC dose. The relatively small proportion of patients with recent or concurrent use of MTX around the time of new TNFi use suggests that TNFi may be replacing, rather than complementing, MTX therapy in many patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/recent-trends-in-medication-usage-for-the-treatment-of-juvenile-idiopathic-arthritis-and-the-influence-of-tnf-inhibitors/