The Determinants of the Distribution of Osteopathic Medicine Physicians in the United States

Objective. This study examined the determinants of the geographic distributions of Doctor of Osteopathic Medicine (DO) physicians in the US. Background. During the past two decades, DO physicians increased significantly and currently account for 7.5% of total physician workforce in the US. Although the geographic distribution of DO has been shown in previous studies, it is unknown what factors that determine the diffusion of DO and how the pattern differs from that of allopathic Medicine physicians (MD). Methods. Total DO Physician data from American Medical Association and Area Resource File from Health Resource and Services Administration were used. Random mixed model adjusted for spatial correlations among counties is used to model the change of DO by county. Results. From 1998 to 2006, the number of DO increased 1.76 for an average county, adjusted for population change and MD change during the same period. For every 100 increase of MD, DO increased 3.66, and for every 1,000 increase of total population, DO increased 0.29, while for every 1,000 increase of elderly population (age 65+), DO decreased 0.71 in an average county. In addition, DOs were more likely to increase among areas where there were more MD, higher percent of managed care enrollees, and more physician assistants. Compared with MD, DO was also more likely to practice in metropolitan areas. Conclusion. Although DO were concentrated among a few states, the distribution at the county level were determined by both local physician workforce change and demographic changes. Grants. None.