Physician Practice Location: An Examination of Physician Workforce Data Sources, Their Spatial Concordance and Reliability

Purpose: This study compares and contrasts locational identification (physician practice ZIP code) between several physician demographic databases and a research team-verified ZIP code to determine spatial concordance. Accuracy of physician location data is critical for both successful national physician workforce planning and for assessing the fulfillment of distinct regional medical school missions.

Methods: Three physician databases; the American Medical Association’s Physician Masterfile, the National Provider and Plan Enumeration System (NPPES), and the Minnesota Board of Medical Practice’s Licensure File were compared against each other as well as a set of actively verified practice location ZIP codes. A sampling frame of medical school alumni from 2003 to 2014 was selected. The sample included alumni from both regional and main campuses. From this alumni sample, a random sample of four hundred individuals were selected for closer examination. Descriptive frequencies are presented for the concordance of ZIP codes for the sample of four hundred alumni.

Findings: From an initial cohort of 2,605 University of Minnesota medical school alumni, a sample of 400 who also possessed a Minnesota medical license were randomly selected to examine concordance rates. The highest rate of concordance was the verified ZIP code and the Minnesota Licensure Board practice ZIP code at 68.8%. Only 42.0% of practice location ZIP codes matched across all databases.

Conclusions: The concordance rate across practice ZIP codes in the databases does not inspire confidence in ability to characterize true physician practice location. Some of the difficulties in defining, identifying and maintaining information on physician practice location are discussed. Without accurate and precise practice location information, the development and implementation of comprehensive national health policies for the United States may face difficulties. The lack of reliable physician practice location data also presents a challenge to regional medical school campuses that depend upon accurate physician location data to evaluate progress toward mission-directed workforce goals.