Specialty drug and health care utilization vary by wage level in employer-sponsored health plans

BACKGROUND: Expenditures on specialty medications for autoimmune conditions (SpRx-AIC) have increased considerably in recent years, raising affordability concerns for employers and other plan sponsors and resulting in greater patient cost-sharing. Among those commercially insured, prior studies have shown differential patterns of health care utilization in association with wage, though no data are available for SpRx-AIC. Notably, out-of-pocket costs associated with SpRx-AIC have been shown to impact medication adherence, particularly for low-income households. OBJECTIVE: To assess the association of wage status on SpRx-AIC and health care services use and cost among employees with employer-sponsored health insurance. METHODS: Employee health care claims and wage data were obtained from the IBM Watson MarketScan database for calendar year 2018. Midyear employee wage data were used as a basis for allocating employees into 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 at lower wage levels. Outcomes included monthly days supply of SpRx-AIC, medication discontinuation rates (medication cessation for >= 90 days), proportion of days covered (PDC), medical services utilization rates per 1,000, and allowed payment amounts. Generalized linear regressions were used to assess differences while adjusting for patient characteristics, including age, gender, plan type, region, median household income, deductible amount, comorbidity index, and psychiatric diagnostic scores. RESULTS: From a sample of more than 2 million enrollees, 148,761 (7.2%) were identified as having an autoimmune disorder of interest. Of those, 17,096 (11.5%) had filled at least one SpRx-AIC prescription. Following adjustment, SpRx-AIC use was significantly less among the lowest wage group compared with the highest wage group (10.1% vs 11.7%; P<0.0001). Days supply was significantly lower in the lowest wage group (244.4 vs 258.0; P<0.001), as was PDC (0.74 vs 0.76; P<0.001). In the lowest wage group, medical services utilization was significantly higher for inpatient admissions (0.08 vs 0.05; P=0.002) and emergency department visits (0.52 vs 0.16; P<0.0001). There were no significant differences among wage groups in SpRx-AIC discontinuation, outpatient services use, or health care costs. CONCLUSIONS: Low-wage employees with autoimmune conditions are significantly less likely to use an SpRx-AIC and have a lower monthly supply and PDC when SpRx-AIC was used. They are more likely to be admitted to the hospital and have more emergency department visits. These findings raise concerns about employer benefit design inequities for SpRx-AIC access and the resulting potential adverse impact on health care costs and employee functional status.