Education and income effects in the use of ambulatory services in the United States: an analysis of the 1970 National Health Interview Survey data.

The roles of education and income as determinants for utilization of ambulatory services in the U.S. are investigated by the application of path analysis to a subsample of the 1970 National Health Interview Survey. The methodology permits the identification of both the direct and indirect effects of each independent variable on utilization within a model that views need as the major determinant of care. Previous findings that income has no direct effect on utilization, while education does, are reaffirmed. Contrary to previous analyses, however, it is shown that income does have a strong indirect effect on utilization via its impact on need arising from chronic conditions, measured as limitation of activity. Individuals in the highest income category have a mean annual visit rate of 4.13, while the rate for those in the lowest is 5.43. Most of the differential, 1.3, is attributable to the lower prevalence of chronic conditions in the highest income bracket. The total effect of education, on the other hand, is only 60% of its direct effect since higher educational attainment is associated with lower levels of chronicity. Disaggregation of direct and indirect effects through the need variables shows that income has a greater effect on utilization than does education.