Combination treatments for patients with rheumatoid arthritis (RA) with an inadequate response to methotrexate (MTX) alone include the addition of a tumor necrosis factor inhibitor (TNFi) or the addition of sulfasalazine (SSZ) and hydroxychloroquine to MTX (triple therapy). We compared persistence and adherence rates between these 2 combination therapies in US veterans and report the reasons for discontinuation of combination treatment in these groups.
Using Veteran's Affairs 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 the proportion of days covered ≥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.
Full persistence at 1 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 from SSZ.
Differences in persistence and adherence between the MTX-TNFi and triple therapy groups appear to be primarily related to adverse drug events that were most often attributed to SSZ.