Equitable access to health care: methodological extensions to the analysis of physician utilization in Canada

In this paper we analyse the distribution of family physician use in Canada to explore whether the stated goal of reasonable access to care has been achieved. We test hypotheses to see whether (a) variations in incidence and quantity of use are independent of need for care as proxied by self-assessed health status and (b) any observed relationship between variations in use and need is independent of other population characteristics. Previous research has conceptual, statistical and data limitations which bring into question the validity of the findings. These limitations are addressed by using more appropriate data, a conditional model for service utilization and correction for self-selectivity of users in the statistical analysis. Variations in need are identified as important and significant in explaining variations in both incidence and quantity of use with the estimated relationship between use and need being positive. Other population characteristics were found to be important and significant in explaining variations in use although household income is not among them. The relationship between use and need is associated with other variables including education, social support and region of residence. These findings suggest that analyses of utilization based on simple multivariate techniques and aggregate data can produce a picture of utilization that conceals important, policy relevant relationships while revealing other relationships that are essentially artifacts of inappropriate aggregation in ways which provide a false sense of achievement.