Specialist Availability and Drug Adherence in Older Adults with Dementia Across Regions of the United States

Abstract

Background: Access to specialists facilitates appropriate Alzheimer’s disease and related dementia (ADRD) medication use and adherence. However, there is little information on the impact of specialists’ availability on ADRD medication adherence, especially in regions of the United States (US) where specialists are scarce, e.g., the Deep South (DS). Objective: To ascertain whether the availability of specialty physicians in the DS and other US regions predicts ADRD medication adherence among community-dwelling older adults Methods: We conducted secondary analyses of claims data for 54,194 Medicare beneficiaries with ADRD in 2013–2015. Medication adherence was measured using the proportion of days covered (PDC). Multivariable-adjusted Modified Poisson regression was used to examine associations of adherence with physicians’ availability by region. Results: The race/ethnicity distribution was 81.44% white, 9.17% black, 6.24% Hispanic, 2.25% Asian, and 1% other; 71.81% were female, and 42.36% were older than 85 years. Beneficiaries across regions differed in all individual and contextual characteristics except sex and comorbidities. Neurologists and psychiatrists’ availability was not significantly associated with adherence (DS = 1.00, 0.97–1.03 & non-DS = 1.01, 1.00–1.01). Race and having ≥1 specialist visits were associated with a lower risk of adherence in both regions (p < 0.0001). Advanced age, dual Medicare/Medicaid eligibility, and living in non-large metropolitan areas, were associated with adherence in the non-DS region. Conclusion: Among older Americans with ADRD, a context defined by specialist availability does not affect adherence, but other context characteristics related to socioeconomic status may. Research should further examine the influence of individual and contextual factors on ADRD treatment among older adults.