The growing body of literature on spatial disparities in health care access has either primarily focused on rural areas or has used counties or states as the level of observation. As a result, little is known about access gaps to primary care within urban settings and the implications of using aggregated data at the county or state level as opposed to smaller area units to inform health policy makers. The objective of this study is to analyze the association between the provider-to-population ratio and the socioeconomic, demographic, and insurance characteristics of the population within the Seattle-Tacoma combined statistical area (CSA) at the census tract level. We implement different spatial econometric models to account for spatial autocorrelation. The provider to population ratio for each census tract is a combination of both primary care providers within the census tract and those outside of the tract but within a 25 minute drive radius, in agreement with the guidelines set by the Department of Health and Human Services (DHHS). Data for primary care providers was collected from the National Provider Identification (NPI) database. Primary care providers are defined as individual physicians, nurse practitioners, and physician assistants whose primary taxonomy code is one of the following: General Practice, Family Medicine, Geriatric Medicine, Internal Medicine, or Primary Care. The socioeconomic, demographic, and insurance characteristics data was collected from the American Community Survey 5-Year estimates (2015).
As of October 2016, Washington State received a five-year demonstration waiver from the Centers for Medicare & Medicaid Services (CMS) which will allow for the transformation of Washington State’s Medicaid system. Initiative 1 of Medicaid Transformation “is intended to build incentives for providers who are committed to changing how we deliver care” (HCA). Part of this initiative would be to ensure the provision of primary care at the local level. In light of this, it is important to inform policy makers about disparities in primary care access not only in rural areas but also in urban areas.