The Korean National Health Insurance extended its coverage to reduce the economic burden of receiving dentures and implants for older adults in 2012 and 2014, respectively. We examined whether the new policy resulted in reduced out-of-pocket dental care expenditure in the eligible population, specifically focusing on low-income adults. We used interrupted time-series analysis (ITSA), a quasi-experimental design, to identify the effects of the policy among persons aged 65 or older. Data were extracted from the Korea Health Panel Survey (KHP; 2008-2017). The main outcome was out-of-pocket expenditures on dental care. The ITSA showed that expenditures decreased annually by 4.5% (RR: 0.96, 95% CI: 0.95-0.96) between 2012 and 2014. However, expenditure increased by 7.8% (RR: 1.08, 95% CI: 1.07-1.08) after 2014. Dental insurance coverage did not contribute to reducing the out-of-pocket expenses for dentures among low-income adults, while coverage of dental implants led to an increase in dental expenditure.
Keywords: causal inference; counterfactual condition; dental insurance; expenditures; interrupted time-series analysis; older adults.