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Low Persistence Rates in Rheumatoid Arthritis Patients Treated with Triple Therapy are Attributed to Adverse Drug Events Associated with Sulfasalazine

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Erhardt DP1, Cannon GW2, Teng CC3, Mikuls TR4, Curtis JR5, Sauer BC3. Arthritis Care Res (Hoboken). 2018 Sep 17. doi: 10.1002/acr.23759. [Epub ahead of print]

Abstract

OBJECTIVE: Combination treatments for rheumatoid arthritis (RA) patients with inadequate response to methotrexate (MTX) alone include the addition of tumor necrosis factor inhibitors (TNFi) or the addition of sulfasalazine (SSZ) and hydroxychloroquine (HCQ) to MTX (triple therapy, TT). We compared persistence and adherence rates between these two combination therapies in US Veterans and report the reasons for discontinuation of combination treatment in these groups.

METHODS: Using Veteran's Affairs (VA) clinical and administrative data from 2006 to 2012, veterans with RA escalating treatment from MTX to MTX-TNFi or triple therapy were examined for a 12-month period after combination initiation. Persistence was defined as treatment without a ≥90-day gap in therapy. Adherence was calculated using proportion of days covered (PDC) ≥80% at 12 months. Matching weights-adjusted models were applied to more closely mimic randomization in this study. The reasons that patients discontinued their combination regimens were identified by chart abstraction.

RESULTS: Full persistence at one year was 45% in the MTX-TNFi patients (n=2,125) and 18% in the triple therapy patients (n=171) (p<0.001). Adherence was higher for the MTX-TNFi group (26%) than the triple therapy group (11%) (p<0.0001). The triple therapy group was associated with significantly more treatment discontinuation, which was most often due to adverse drug events (ADE) from SSZ.

CONCLUSION: Differences in persistence and adherence between the MTX-TNFi and triple therapy groups appear to be primarily related to ADE that were most often attributed to SSZ.