Sociodemographic, disease, health system, and contextual factors affecting the initiation of biologic agents in rheumatoid arthritis: a longitudinal study

Objective: To analyze the effect of sociodemographic, disease, and health system characteristics and contextual features about the community of residence on the subsequent initiation of treatment with biologic agents for rheumatoid arthritis (RA).

Methods: We analyzed data from the University of California, San Francisco Rheumatoid Arthritis Panel Study for the years 1999-2011. Principal data collection was by a structured annual phone survey. We estimated Kaplan-Meier curves of the time until initiation of biologic agents, stratified by age and income. We also used Cox regression to estimate the effect of individual-level sociodemographic and medical factors, contextual-level socioeconomic status measures, and density of health providers in the local community on the probability of initiating therapy with biologic agents for RA.

Results: In total, 527 persons were included in the panel in 1999, and 229 persons (44%) had initiated therapy with biologic agents by 2011. In multivariable Cox regression models, age <70 years (hazard ratio [HR] for ages 19-54 years 1.89 [95% confidence interval (95% CI) 1.24-2.87] and HR for ages 55-69 years 1.25 [95% CI 0.84-1.87]), Hispanic ethnicity (HR 2.02 [95% CI 1.05-3.86]), household income ≥$30,000/year (HR 1.61 [95% CI 1.12-2.32]), being married or with a partner (HR 1.39 [95% CI 1.00-1.92]), and residence in rural environments (HR 1.96 [95% CI 1.28-2.99]) were associated with a higher probability of initiating biologic agents. Having no (HR 0.18 [95% CI 0.08-0.40]) or only 1-4 rheumatology visits in the year prior to interview (HR 0.60 [95% CI 0.45-0.81]) and living in an area with ≥1 federally qualified health centers (HR 0.63 [95% CI 0.41-0.96]) were associated with a lower probability.

Conclusion: The probability of initiating therapy with biologic agents is affected by sociodemographic and health system characteristics as well as the nature of the community of residence, resulting in disparities in access to these medications.