Specialty drug use for autoimmune conditions varies by race and wage among employees with employer-sponsored health insurance

BACKGROUND: The relationship between race and ethnicity, wage status, and specialty medication (SpRx) use among employees with autoimmune conditions (AICs) is poorly understood. Insight into sociodemographic variations in use of these medications can inform health equity improvement efforts. OBJECTIVE: To assess the association of race and ethnicity and wage status on SpRx use and adherence patterns among employees with AICs enrolled in employersponsored health insurance. METHODS: In this observational, retrospective cohort analysis, data were obtained from the IBM Watson MarketScan database for calendar year 2018. Employees were separated into race and ethnicity subgroups based on employer -provided data. Midyear employee wage data were used to allocate employees into the following annual income quartiles: $47,000 or less, $47,001-$71,000, $71,001-$106,000, and $106,001 or more. The lowest quartile was further divided into 2 groups ($35,000 or less and $35,001-$47,000) to better evaluate subgroup differences. Outcomes included monthly days SpRx-AIC supply, proportion of days covered (PDC), and medication discontinuation rates. Generalized linear regressions were used to assess differences while adjusting for patient and other characteristics. RESULTS: From a sample of more than 2,000,000 enrollees, race and ethnicity data were available for 617,117 (29.8%). Of those, 47,839 (7.8%) were identified as having an AIC of interest, with prevalence rates of AICs differing by race within wage categories. Among those with AICs, 5,358 (11.2%) had filled at least 1 SpRx-AIC prescription. Following adjustment, except for the highest wage category, prevalence of SpRx-AIC use was significantly less among Black and Hispanic subpopulations. Black patients had significantly lower SpRx-AIC use rates than White patients (<=$35,000: 4.9 vs 9.4%, >$35,000-$47,000: 5.5 vs 10.6%, >$47,000- $71,000: 8.5 vs 11.1%, and >$71,000-$106,000: 9.1 vs 12.7%; P < 0.001 for all). For Hispanic patients, prevalence rates were significantly lower than White patients in 3 different wage categories (<=$35,000: 4.5 vs 9.4%, >$35,000-$47,000: 6.1 vs 10.6%, and >$71,000-$106,000: 8.6 vs 12.7%; P < 0.001). PDC and 90 -day discontinuation rates did not differ among race and ethnicity groups within the respective wage bands. CONCLUSIONS: Race and ethnicity and wage -related disparities exist in SpRx use, but not PDC or discontinuation rates for treatment of AICs among non-White and low-income populations with employer -sponsored insurance, and may adversely impact clinical outcomes.