What explains differences in waiting times for health care across socioeconomic status?

In publicly funded health systems, waiting times act as a rationing mechanism that should be based on need rather than socioeconomic status. However, several studies suggest that individuals with higher socioeconomic status wait less. Using individual-level data from administrative registers, we estimate and explain socioeconomic inequalities in access to publicly funded care for seven planned hospital procedures in Denmark. For each procedure, we first estimate the association between patients' waiting time for health care and their socioeconomic status as measured by income and education, controlling for patient severity. Then, we investigate how much of the association remains after controlling for (i) other individual characteristics (patients' family status, labor market status, and country of origin) that may be correlated with income and education, (ii) possible selection due to patients' use of a waiting time guarantee, and (iii) hospital factors which allow us to disentangle whether inequalities in waiting times arise across hospitals or within the hospital. Only for a few procedures, we find inequalities in waiting times related to income and education. These inequalities can be explained mostly by geographical and institutional factors across hospitals. But we also find inequalities for some procedures in relation to non-Western immigrants within hospitals.