Access to injectable biologic medications by medicare beneficiaries: geographic distribution of US dermatologist prescribers.

Injectable biologics (IB) are important in dermatology and we sought to examine the distribution of US IB-prescribing dermatologists. We used Centers for Medicare and Medicaid Services Medicare Provider Utilization and Payment Data: Part D for 2013-2015. The density of dermatologists who prescribe IB (etanercept, adalimumab, ustekinumab, secukinumab) in each US county, represented as number of dermatologists per 100,000 Medicare Part D beneficiaries, was calculated. 2,992 dermatologists (26.3% of dermatologists) prescribed IB in this study. The national density of IB-prescribing dermatologists was 7.22. Only 778 counties (24.8%) have at least one IB-prescribing dermatologist. The densities of IB-prescribing dermatologists in metropolitan counties were 8.07-8.12. The densities of IB-prescribing dermatologists were 4.55 and 6.51 for urban populations of greater than 20,000 people adjacent and non-adjacent to metropolitan areas, respectively. Urban counties with populations between 2,500-19,999 and adjacent to a metropolitan area had a density of 2.03 and urban counties with the same population and not adjacent to a metropolitan area had a density of 2.84. Completely rural or urban counties with populations under 2,500 people had densities between 2.31-2.35. There are disparities in the availability of IB-prescribing dermatologists across urban-rural geographic settings in the US.