Examining Time to Initiation of Biologic Disease-modifying Antirheumatic Drugs and Medication Adherence and Persistence Among Texas Medicaid Recipients With Rheumatoid Arthritis

Abstract

Purpose: Little is known about the transition from nonbiologic disease-modifying antirheumatic drugs (DMARDs) to biologic DMARDs or about individual nonbiologic DMARD use patterns among patients with rheumatoid arthritis (RA). This study examined time to initiation of biologic DMARDs and nonbiologic DMARD medication adherence and persistence among Texas Medicaid recipients with RA taking nonbiologic DMARDs.

Methods: In this retrospective study (July 1, 2003-December 31, 2010) of the Texas Medicaid database, patients were aged 18 to 62 years at index, were diagnosed with RA (International Classification of Diseases, Ninth Revision, Clinical Modification, code 714.xx), had no claims for nonbiologic or biologic DMARDs in the preindex period, and had a minimum of 2 prescription claims for the same nonbiologic DMARD in the postindex period. Kaplan-Meier survival analysis and log-rank tests were used to compare time to initiation of biologic DMARDs according to nonbiologic DMARD type and therapy. Adherence and persistence were examined according to nonbiologic type and therapy by using ANOVA models and χ(2), Duncan, and t tests.

Findings: On average, patients were 47.9 (± 10.4) years of age, mostly female (89.1%) and Hispanic (55.2%). Methotrexate (MTX) and leflunomide (LEF) users took the shortest time to initiate biologic DMARDs (207 [190] days and 188 [205] days, respectively). LEF users had the highest mean adherence of 37.5% (27.5%), which was similar to MTX users (35.7% [26.9%]), whereas dual-therapy users had the lowest mean adherence at 17.1% (14.4%). Sulfasalazine users (108 [121] days) had the lowest persistence, whereas LEF (227 [231] days) and MTX (211 [222] days) users had the longest persistence. Nonbiologic DMARD monotherapy users were more adherent than dual-therapy users (32.6% [25.8%] vs 17.1% [14.4%]).

Implications: These results should be interpreted in light of some study limitations, such as using proportion of days covered as a proxy for adherence, not having clinical data to control for RA severity, and lack of generalizability to all US populations. Given the study findings, both clinicians and other decision makers may want to investigate the potential driving factors of initiation of biologic DMARDs to provide effective RA management and consider patient education programs to enhance medication adherence and persistence to RA medications.

Keywords: Texas Medicaid; adherence; biologic disease-modifying antirheumatic drugs; initiation; nonbiologic disease-modifying antirheumatic drugs; rheumatoid arthritis.