title: Economic expansion is a major determinant of physician supply and utilization.
abstract: OBJECTIVE
  To assess the relationship between levels of economic development and the supply and utilization of physicians.
  
  
  METHODS
  Data were obtained from the American Medical Association, American Osteopathic Assocation, Organization for Economic Cooperation and Development (OECD), Bureau of Health Professions, Bureau of Labor Statistics, Bureau of Economic Analysis, Census Bureau, Health Care Financing Administration, and historical sources.
  
  
  METHODS
  Economic development, expressed as real per capita gross domestic product (GDP) or personal income, was correlated with per capita health care labor and physician supply within countries and states over periods of time spanning 25-70 years and across countries, states, and metropolitan statistical areas (MSAs) at multiple points in time over periods of up to 30 years. Longitudinal data were analyzed in four complementary ways: (1) simple univariate regressions; (2) regressions in which temporal trends were partialled out; (3) time series comparing percentage differences across segments of time; and (4) a bivariate Granger causality test. Cross-sectional data were assessed at multiple time points by means of univariate regression analyses.
  
  
  RESULTS
  Under each analytic scenario, physician supply correlated with differences in GDP or personal income. Longitudinal correlations were associated with temporal lags of approximately 5 years for health employment and 10 years for changes in physician supply. The magnitude of changes in per capita physician supply in the United States was equivalent to differences of approximately 0.75 percent for each 1.0 percent difference in GDP. The greatest effects of economic expansion were on the medical specialties, whereas the surgical and hospital-based specialties were affected to a lesser degree, and levels of economic expansion had little influence on family/general practice.
  
  
  CONCLUSIONS
  Economic expansion has a strong, lagged relationship with changes in physician supply. This suggests that economic projections could serve as a gauge for projecting the future utilization of physician services.
authors.affiliation: Health Policy Institute, Medical College of Wisconsin, Milwaukee 53202, USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Cooper
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Getzen
authors.forename: Prakash
authors.initials: P
authors.lastname: Laud
mesh_terms: D003430:Cross-Sectional Studies; D005544:Forecasting; D005102:Health Expenditures; D006301:Health Services Needs and Demand / Q000191:economics / Q000639:trends; D006302:Health Services Research; D006280:Health Workforce / Q000191:economics / Q000706:statistics & numerical data / Q000639:trends*; D006801:Humans; D007182:Income; D008137:Longitudinal Studies; D017059:Models, Econometric; D010820:Physicians / Q000706:statistics & numerical data / Q000600:supply & distribution*; D012044:Regression Analysis; D014481:United States