Socioeconomic Status and Not Race Associated with Delay in Diagnosis and Treatment of Rheumatoid Arthritis

Background/Purpose: Ethnic disparities in outcomes of RA patients have been attributed to delayed presentation to specialty care and access to DMARDs, greater disease burden, and less years of education. Recent literature supports a role for socioeconomic status (SES) as a determinant of RA disease status, including clinical disease activity measures, mortality, seropositivity, and treatment delays. The purpose of this analysis was to delineate the association of SES to referral time and start of first DMARD in a diverse cohort of RA patients.

Methods: Ethnic Minority RA Consortium (EMRAC) participants with recorded dates of initial RA symptom, diagnosis and first disease-modifying drug (DMARD) were abstracted for analysis. Socio-demographic (age, gender, race, years of education, tobacco use), and RA disease status (disease duration, erosions, tender and swollen joints, RAPID3) at enrollment was documented.  An estimate of SES was derived from the median housing income of the city of each enrollment site.  Median incomes less than two-fold the 2014 poverty line ($47,700) defined lower SES status.  Delays of ³ one-year for diagnosis and DMARD initiation were both defined from date of initial RA symptom. Logistic regression was used to model the association between risk factors and a one-year delay of diagnosis and DMARD initiation.

Results: 269 EMRAC participants with self-reported race/ethnicity and disease history were evaluated; 202 (75%) were female.  The average values for the following parameters were: age 60.4 (±15.8) years, disease duration 13.6 (±10.8) years, and education 12.5 (±3.0) years. A majority (200 [74.4%]) of EMRAC participants were enrolled at sites serving lower than the twice poverty line. Significant differences in participantsÕ age, education years, disease activity and race were observed between SES groups (Table). Based upon the logistic regression model, being below the twice poverty line was significantly associated with the increased odds of ³ one-year diagnosis delay [3-fold increase; odds ratio (OR) = 4.0, 95% CI: (1.6, 10.1), P=0.003)] as well as increased odds of DMARD initiation delay [1.4 fold increase, OR = 2.4, 95% CI: (1.1, 5.06), P=0.027)]. There was no association between either diagnosis or DMARD delay and race. However tender joint counts were associated with increased odds of DMARD delay (per tender joint increase OR 1.1, 95% CI (1.01, 1.14), P = 0.028).

Conclusion: In a diverse ethnic cohort, disparity in income as an estimate of SES was a strong predictor of delay in referral to a rheumatologist and start of first DMARD.  Policies that improve access to specialty care and RA medications must be paralleled by improvements in overall SES of individuals in order to minimize the impact of disease. Table. Enrollment Characteristics by being Below or Above the Poverty Line