Factors associated with the initiation of biologic disease-modifying antirheumatic drugs in Texas Medicaid patients with rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is a progressive autoimmune disorder of joints that is associated with high health care costs, yet guidance is lacking on how early to initiate biologic disease-modifying antirheumatic drugs (DMARDs), a class of medications that is the major cost driver in RA management. Few studies have examined the factors associated with the transition from nonbiologic DMARDs, the first-line therapy for RA, to biologic DMARDs in RA patients. 

OBJECTIVE: To examine patient sociodemographics, medication use patterns, and clinical characteristics associated with initiation of biologic DMARDs.  

METHODS: This was a retrospective study using the Texas Medicaid prescription and medical claims database from July 1, 2003-December 31, 2010. Adults (aged 18-63 years) with an RA diagnosis (ICD-9-CM code 714.xx), no nonbiologic DMARD or biologic DMARD use during the 6-month pre-index period, and a minimum of 2 prescription claims for the same nonbiologic DMARD during the post-index period were included in the study. The index date was defined as the date when the first nonbiologic DMARD claim was made. Predictors of initiation of biologic DMARDs were age, gender, race, adherence (proportion of days covered), persistence to nonbiologic DMARDs, comorbidity (Charlson Comorbidity Index [CCI]), pain medication use, glucocorticoid use, and rheumatologist visit. Logistic regression was used to examine the factors associated with the initiation of biologic DMARDs.  

RESULTS: A total of 2,714 patients were included. After controlling for patient characteristics, logistic regression showed, that compared with methotrexate (MTX) users, sulfasalazine (SSZ) and hydroxychloroquine (HCQ) users were less likely to initiate biologic DMARDs by 69.0% (OR = 0.310, 95% CI = 0.221-0.434, P  less than  0.0001) and 79.9% (OR = 0.201, 95% CI = 0.152-0.265, P  less than  0.0001), respectively. Nonbiologic DMARD dual therapy users were 39.1% less likely to initiate biologic DMARDs compared with nonbiologic DMARD monotherapy users (OR = 0.609, 95% CI = 0.463-0.803, P = 0.0004). With each year increase in age, patients were 1.6% less likely to start biologic DMARDs (OR = 0.984, 95% CI = 0.975-0.993, P = 0.0006). Compared with glucocorticoid users, glucocorticoid nonusers were 53.8% less likely to start on biologic DMARDs (OR = 0.462, 95% CI = 0.372-0.573, P  less than  0.0001). Patients with CCI scores of ≥ 3 were approximately 1.6 times more likely to initiate biologic DMARDs than those with CCI scores of 1 (OR = 1.618, 95% CI = 1.228-2.132, P = 0.0006). 

CONCLUSIONS: Younger age, CCI scores ≥3, glucocorticoid use, MTX users (vs. SSZ and HCQ users), and nonbiologic DMARD monotherapy users (vs. dual therapy users) were significantly associated with higher likelihood to initiate biologic DMARDs. Recognizing these potential factors that drive the initiation of biologic DMARDs in this patient population, health care providers and Texas Medicaid should take measures to achieve optimal therapy for RA patients through thorough RA medication evaluation, well-structured RA monitoring programs, and patient education.