Background/Purpose: Ankylosing spondylitis (AS) is characterized by chronic debilitating inflammation of the spine and/or sacroiliac joints. Several biologic agents have been approved for the treatment of AS. In some instances, physicians and patients may discontinue or switch biologics during the course of therapy. These treatment patterns are not well characterized and have potential clinical implications. The objective of this study was to characterize and understand the treatment patterns of AS patients on subcutaneous biologics therapy.

Methods: We conducted a retrospective analysis of medical and pharmacy claims data from the MarketScan commercial claims database (United States). Biologic-naïve AS patients (no biologic therapy in the previous 12 months) were identified who initiated a biologic agent (etanercept, adalimumab, or golimumab) during the period from January 1, 2011, to December 31, 2012, and were continuously enrolled in a prescription drug benefit program for 12  months prior to, and 18 months following, their first biologic use. Demographic, clinical, and treatment information were analyzed.

Results: 382 AS patients met the criteria for analysis (index biologic: adalimumab, n=202 [52.9%]; etanercept, n=157 [41.1%]; golimumab, n=23 [6.0%]).   They had a mean age 42.5 yrs and 66.5% male. The most common comorbidities were hypertension (18.8%), hyperlipidemia (12.6%), depression (8.9%), and uveitis (7.9%). During the follow-up period, 214 patients (56.0%) were continuous users of the index treatment (no gaps in therapy >180 days or no therapy switches for 12 months), while 168 (44.0%) discontinued (had a gap in therapy >180 days with the index therapy or switched to another therapy). Among patients who discontinued their index therapy, 53 (13.9% of the total group) switched to another agent with a treatment gap of ≤180 days; 14 (3.7%) had a gap in therapy >180 days, but restarted on their index therapy while 6 (1.6%) restarted with a different biologic therapy after discontinuation of index biologic. Among continuous users (no gap >180 days) dose escalation was infrequent: adalimumab, 9 patients (7.6%) with above label dosing (>40 mg every 2 weeks); etanercept, 1 patient (1.1%) (>50 mg/wk); golimumab 0 patients (0%) received a (>50 mg/month).

Conclusion: Almost half of AS patients will discontinue their index biologics in the year following initiation of use.  Of those who continued therapy adherence was high and the approved label dosing was frequently used. Future studies are needed to further define treatment patterns, the reasons for discontinuation of the index biologic, switching and importantly the pharmacoeconomic impact of these patterns.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/treatment-patterns-of-subcutaneous-biologic-agent-use-among-patients-with-ankylosing-spondylitis/