Escalation to Biologics After Methotrexate Among US Veterans with Rheumatoid Arthritis Grouped by Rural Versus Urban Areas.

Background: Racial and ethnic disparities in rheumatoid arthritis (RA) outcomes are well recognized. However, whether disparities in RA treatment selection and outcomes differ by urban versus rural residence, independent of race, have not been studied. Our objective was to evaluate whether biologic disease modifying anti-rheumatic drugs (bDMARD) initiation after methotrexate use differs by rural versus urban residence among Veterans with RA.

Methods: In this retrospective cohort study utilizing national U.S. Veterans Affairs databases, we identified adult patients with RA based on presence of diagnostic codes and DMARD use. We included patients receiving an initial prescription of methotrexate (index date) between 2005 and 2014, with data through 2016 used for follow-up. Urban-rural status was categorized using the Veteran Health Administration's Urban/Rural classification. Our primary outcome of interest was time to biologic initiation within two years of starting methotrexate. Multivariable Cox proportional hazards models were conducted adjusting for demographics, comorbidities, and rheumatoid factor or anti-CCP positivity.

Results: Among 17,395 veterans with RA (88% male, 42% with rural residence) fulfilling eligibility criteria, 3,259 (19%) initiated a biologic within the first two years of follow up. In multivariable models, residence in an urban area was associated with a statistically significant higher biologic use compared to rural areas (adjusted hazard ratio (aHR) 1.10, 95% CI 1.02-1.18).

Conclusion: Our study found only modest differences in initiation of biologic therapies among rural versus urban residing Veterans with RA in the VA healthcare system. These findings suggest that disparities are not easily explained by rurality within the VA healthcare system.