Impact of differential copayment on patient healthcare choice: evidence from South Korean National Cohort Study

Objective We evaluate the effectiveness of mild disease differential copayment policy aimed at reducing unnecessary patient visits to secondary/tertiary healthcare institutions in South Korea. Design Retrospective study using difference-in-difference design. Setting Sample Research database provided by the Korean National Health Insurance Service, between 2010 and 2013. Participants 206 947 patients who visited healthcare institutions to treat mild diseases during the sample period. Methods A linear probability model with difference-in-difference approach was adopted to estimate the changes in patients' healthcare choices associated with the differential copayment policy. The dependent variable was a binary variable denoting whether a patient visited primary healthcare or secondary/tertiary healthcare to treat her/his mild disease. Patients' individual characteristics were controlled with a fixed effect. Results We observed significant decrease in the proportion of patients choosing secondary/tertiary healthcare over primary healthcare by 2.99 per cent point. The decrease associated with the policy was smaller by 14% in the low-income group compared with richer population, greater by 19% among the residents of Seoul metropolitan area than among people living elsewhere, and greater among frequent healthcare visitors by 33% than among people who less frequently visit healthcare. Conclusion The mild disease differential copayment policy of South Korea was successful in discouraging unnecessary visits to secondary/tertiary healthcare institutions to treat mild diseases that can be treated well in primary healthcare.

Automated summary

The mild disease differential copayment policy in South Korea successfully reduced unnecessary visits to secondary/tertiary healthcare institutions for treating mild diseases. The policy had a smaller effect on the low-income group and a greater effect on frequent healthcare visitors, indicating its effectiveness in promoting primary healthcare utilization.