Treatment Patterns with Disease-Modifying Antirheumatic Drugs in US Veterans with Newly Diagnosed Rheumatoid Arthritis, Psoriatic Arthritis, or Ankylosing Spondylitis

BACKGROUND: Delays in treatment for inflammatory arthritis (IA) are associated with unfavorable outcomes, including impaired quality of life, irreversible joint damage, and disability. OBJECTIVE: To characterize treatment initiation patterns in veterans with newly diagnosed rheumatoid arthritis (RA), psoriatic arthritis (PsA), or ankylosing spondylitis (AS). METHODS: ICD-9/10-CM codes and natural language processing were used to identify incident cases of RA, PsA, or AS between January 1, 2007, and December 31, 2015, in patients enrolled in the Veterans Health Administration. Patterns of treatment initiation and nontreatment with disease-modifying antirheumatic drugs (DMARDs) were assessed in the 12-month follow-up period after the incident diagnosis. Outcomes included the percentage of veterans treated with a DMARD, the mean time to the initial DMARD after diagnosis, and the percentage of veterans who accessed rheumatology care before DMARD initiation. To assess outcomes over time, veterans were grouped by year of initial IA diagnosis. Additionally, outcomes were compared between nonbiologic and biologic DMARDs and among IA subtypes (RA, PsA, and AS). Groups were statistically compared with 95% confidence intervals. RESULTS: The population consisted of 12,118 IA veterans (9,711 RA, 1,472 PsA, and 935 AS), with 91.3% males and a mean age of 63.7 years. The percentage of veterans treated with >= 1 DMARD (nonbiologic or biologic) during the 12-month follow-up period increased from 48.8% in 2007 to 66.4% in 2015. In veterans diagnosed with IA in 2015, DMARD treatment was more common for PsA patients (72.9%) and RA patients (68.6%) than for AS patients (28.9%). In the subset treated with a DMARD within 12 months after diagnosis, the mean time to the initial DMARD after diagnosis did not change throughout the observation period (35.5 days for RA, 43.9 days for PsA, and 59.5 days for AS). Rheumatology specialty care was accessed by 87.4% of veterans treated with a nonbiologic DMARD and 92.2% of veterans treated with a biologic DMARD, in patients diagnosed in 2015. CONCLUSIONS: DMARD treatment rates during the initial 12 months after diagnosis increased between 2007 and 2015, but nontreatment remained common, particularly in veterans with AS. The time to treatment after diagnosis was stable over time; it was shortest for RA, intermediate for PsA, and longest for AS. DMARD treatment was uncommon in veterans who did not access rheumatology specialty care. Copyright (C) 2019, Academy of Managed Care Pharmacy. All rights reserved.