Expansion of Korea's Special Estimate Case System and changes in out-of-pocket expenditure: an interrupted time-series analysis
- 1Health Insurance Research Institute, National Health Insurance Service
- 2The Institute for Occupational Health, Yonsei University College of Medicine
- 3Graduate School of Public Health, Yonsei University
Abstract
Background: Since the 2000s, Korea has expanded its National Health Insurance coverage through the implementation and expansion of the Special Estimate Case System. This study examined changes in the proportion of out-of-pocket (OOP) expenditure associated with these policy changes.
Methods: We analyzed nationwide National Health Insurance Database data from 2002 to 2024. Interrupted time-series (ITS) analysis using monthly data was performed to examine changes in the proportion of OOP expenditure relative to total medical expenditure associated with the implementation (September 2005) and expansion (July 2009) of the Special Estimate Case System. An additional controlled interrupted time-series (CITS) analysis compared changes between care covered and not covered under the system following the 2009 expansion.
Results: The proportion of OOP expenditure decreased from 27.1% in 2005 to 25.3% in 2006 and from 25.4% in 2009 to 24.3% in 2010. The ITS analysis showed immediate reductions of 1.78 percentage points following implementation and 0.47 percentage points following expansion for total care. In the additional CITS analysis, the differential reduction following the 2009 expansion was 3.11 percentage points for total care, indicating a greater reduction in the OOP expenditure proportion for care covered under the system than for care not covered under the system.
Conclusion: The implementation and expansion of the Special Estimate Case System were associated with reductions in the proportion of OOP expenditure, although the patterns differed by type of care and healthcare institution. After excluding medical expenditure for care covered under the system, OOP expenditure proportions were closer to the statutory copayment rates under the NHI. These findings may inform future policy discussions on the selection of eligible diseases and patient groups and the setting of copayment rates under the Special Estimate Case System.
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BibTeX
@article{bae2026expansion,
title = {{Expansion of Korea's Special Estimate Case System and changes in out-of-pocket expenditure: an interrupted time-series analysis}},
author = {Suk Won Bae and Jeongha Kim and Wha Me Park},
journal = {Frontiers in Public Health},
year = {2026},
month = oct,
doi = {10.3389/fpubh.2026.1927340},
url = {https://www.frontiersin.org/articles/10.3389/fpubh.2026.1927340/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Expansion of Korea's Special Estimate Case System and changes in out-of-pocket expenditure: an interrupted time-series analysis
AU - Suk Won Bae
AU - Jeongha Kim
AU - Wha Me Park
PY - 2026
DA - 2026/10/13
JO - Frontiers in Public Health
DO - 10.3389/fpubh.2026.1927340
UR - https://www.frontiersin.org/articles/10.3389/fpubh.2026.1927340/full
AB - Background: Since the 2000s, Korea has expanded its National Health Insurance coverage through the implementation and expansion of the Special Estimate Case System. This study examined changes in the proportion of out-of-pocket (OOP) expenditure associated with these policy changes. Methods: We analyzed nationwide National Health Insurance Database data from 2002 to 2024. Interrupted time-series (ITS) analysis using monthly data was performed to examine changes in the proportion of OOP expenditure relative to total medical expenditure associated with the implementation (September 2005) and expansion (July 2009) of the Special Estimate Case System. An additional controlled interrupted time-series (CITS) analysis compared changes between care covered and not covered under the system following the 2009 expansion. Results: The proportion of OOP expenditure decreased from 27.1% in 2005 to 25.3% in 2006 and from 25.4% in 2009 to 24.3% in 2010. The ITS analysis showed immediate reductions of 1.78 percentage points following implementation and 0.47 percentage points following expansion for total care. In the additional CITS analysis, the differential reduction following the 2009 expansion was 3.11 percentage points for total care, indicating a greater reduction in the OOP expenditure proportion for care covered under the system than for care not covered under the system. Conclusion: The implementation and expansion of the Special Estimate Case System were associated with reductions in the proportion of OOP expenditure, although the patterns differed by type of care and healthcare institution. After excluding medical expenditure for care covered under the system, OOP expenditure proportions were closer to the statutory copayment rates under the NHI. These findings may inform future policy discussions on the selection of eligible diseases and patient groups and the setting of copayment rates under the Special Estimate Case System.
SN - 2296-2565
ER -