Economic Burden and Treatment Patterns of Cycling between Conventional Synthetic Disease-modifying Antirheumatic Drugs Among Biologic-treated Patients with Rheumatoid Arthritis

Purpose: To assess the economic outcomes and treatment patterns among patients with rheumatoid arthritis (RA) who used 1, 2, or 3 or more conventional synthetic disease-modifying antirheumatic drugs (DMARDs) before receiving a biologic therapy.

Methods: Adult patients with ≥2 RA diagnoses (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] codes 714.xx) on different dates, ≥1 claim for a conventional synthetic DMARD, and ≥1 claim for a biologic DMARD were identified from a large commercial claims database. The initiation date of the first biologic DMARD was defined as the index date. Based on the number of distinct conventional synthetic DMARDs initiated between the first RA diagnosis and the index date, patients were classified into 3 cohorts: those who used 1, 2, or 3 or more conventional synthetic DMARDs. Baseline characteristics were measured 6 months preindex date and compared between the 3 cohorts. All-cause health care costs (in 2014 US$) were compared during the follow-up period (12 months postbiologic initiation) using multivariable gamma models adjusting for baseline characteristics. Time to discontinuation of the index biologic DMARD and time to switching to a new DMARD were compared using multivariable Cox proportional hazards models.

Findings: The 1, 2, and 3 or more conventional synthetic DMARD cohorts included 6215; 3227; and 976 patients, respectively. At baseline, patients in the 3 or more conventional synthetic DMARD cohort had the least severe RA, as indicated by the lowest claims-based index for RA severity score (1 vs 2 vs 3 or more = 6.1 vs 5.9 vs 5.8). During the study period, there was a significant association between number of conventional synthetic DMARDs and higher all-cause total health care costs (adjusted mean difference, 1 vs 2: $772; P < 0.001; 2 vs 3 or more: $2390; P < 0.001). The all-cause medical and pharmacy costs were also significantly higher with the increasing number of conventional synthetic DMARDs. Patients who cycled more conventional synthetic DMARDs were also more likely to switch treatment after biologic initiation (1 vs 2: adjusted hazard ratio = 0.89; P = 0.005; 2 vs 3 or more: adjusted hazard ratio = 0.89; P = 0.087). There were no differences in index biologic discontinuation between the 3 cohorts.

Implications: Patients with RA who cycled more conventional synthetic DMARDs had increased economic burden in the 12 months following biologic initiation and were more likely to switch therapy. These results highlight the importance of timely switching to biologic DMARDs for the treatment of RA.