{
  "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.\n\nMethods: 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.\n\nResults: 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.\n\nConclusion: 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.",
  "abstract_shown": true,
  "affiliations": [
    "Health Insurance Research Institute, National Health Insurance Service",
    "The Institute for Occupational Health, Yonsei University College of Medicine",
    "Graduate School of Public Health, Yonsei University"
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Suk Won Bae"
    },
    {
      "affs": [
        0
      ],
      "name": "Jeongha Kim"
    },
    {
      "affs": [
        1,
        2
      ],
      "name": "Wha Me Park"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5deg24hknx6zx.bib",
  "cited_by": 0,
  "doi": "10.3389/fpubh.2026.1927340",
  "fulltext_url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC13710395/",
  "id": "5deg24hknx6zx",
  "issns": [
    "2296-2565"
  ],
  "landing_url": "https://www.frontiersin.org/articles/10.3389/fpubh.2026.1927340/full",
  "language": "en",
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "heading",
      "Original Research"
    ],
    [
      "openalex",
      "2003|Healthcare Systems and Reforms"
    ]
  ],
  "openalex": "W7221710483",
  "pdf_url": "https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2026.1927340/pdf",
  "pmcid": "PMC13710395",
  "pmid": "42947897",
  "published": "2026-10-13",
  "publisher": "Frontiers Media SA",
  "ris": "https://research.draconitic.com/paper/5deg24hknx6zx.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:22Z",
      "native_id": "10.3389/fpubh.2026.1927340",
      "source": "crossref",
      "url": "https://www.frontiersin.org/articles/10.3389/fpubh.2026.1927340/full"
    },
    {
      "first_seen": "2026-10-31T12:21:22Z",
      "native_id": "PMC13710395",
      "source": "pmc",
      "url": "https://doi.org/10.3389/fpubh.2026.1927340"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "issn:2296-2565",
      "subfield": "epidemiology-public-health"
    }
  ],
  "title": "Expansion of Korea's Special Estimate Case System and changes in out-of-pocket expenditure: an interrupted time-series analysis",
  "title_text": "Expansion of Korea's Special Estimate Case System and changes in out-of-pocket expenditure: an interrupted time-series analysis",
  "type": "peer-reviewed",
  "updated_at": "2026-10-31T12:21:22Z",
  "url": "https://research.draconitic.com/paper/5deg24hknx6zx",
  "venue": "Frontiers in Public Health",
  "versions": []
}