Fig 1. Association between equivalent income and outpatient utilization rate in all subjects.

Adjusted means and 95% confidence intervals (CIs) are shown. The number of subjects was 222,259. The probabilities were predicted by the Generalized Estimating Equation (GEE) with binomial distribution and logit function considering the correlation within households. This model has main associations (age, sex, and equivalent income), two-way interactions (age*sex, age*equivalent income, and sex*equivalent income), three-way interaction (age*sex*equivalent income), and two covariates (the number of family members and residence).