- Adjusting for Confounders in Outcome Studies Using the Korea National Health Insurance Claim Database: A Review of Methods and Applications
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Seung Jin Han, Kyoung Hoon Kim
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J Prev Med Public Health. 2024;57(1):1-7. Published online November 16, 2023
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DOI: https://doi.org/10.3961/jpmph.23.250
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Abstract
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- Objectives
Adjusting for potential confounders is crucial for producing valuable evidence in outcome studies. Although numerous studies have been published using the Korea National Health Insurance Claim Database, no study has critically reviewed the methods used to adjust for confounders. This study aimed to review these studies and suggest methods and applications to adjust for confounders.
Methods We conducted a literature search of electronic databases, including PubMed and Embase, from January 1, 2021 to December 31, 2022. In total, 278 studies were retrieved. Eligibility criteria were published in English and outcome studies. A literature search and article screening were independently performed by 2 authors and finally, 173 of 278 studies were included.
Results Thirty-nine studies used matching at the study design stage, and 171 adjusted for confounders using regression analysis or propensity scores at the analysis stage. Of these, 125 conducted regression analyses based on the study questions. Propensity score matching was the most common method involving propensity scores. A total of 171 studies included age and/or sex as confounders. Comorbidities and healthcare utilization, including medications and procedures, were used as confounders in 146 and 82 studies, respectively.
Conclusions This is the first review to address the methods and applications used to adjust for confounders in recently published studies. Our results indicate that all studies adjusted for confounders with appropriate study designs and statistical methodologies; however, a thorough understanding and careful application of confounding variables are required to avoid erroneous results.
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Summary
Korean summary
건강보험청구자료를 사용한 성과연구에서는 교란요인 통제가 중요하다. 최근 발표된 연구들은
연구설계와 통계 분석 과정에 적절하게 교란요인을 통제하였다. 연구의 질을 높이기 위해서는 건강보험청구자료에서 수집 가능한 교란 요인에 대한 이해와 방법론적 가이드라인이 요구된다.
Key Message
All recently published studies using Health Insurance Claims Database adjusted for confounders with appropriate study designs and statistical methodologies.
The review suggests the need for careful application of confounding variables and the methodological guidance to improve the quality of outcome studies.
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Citations
Citations to this article as recorded by
- Factors Associated With Receiving Early Post-Discharge Follow-up Care in Patients With Schizophrenia
Song Ee Che, Kyoung-Hoon Kim Journal of Korean Medical Science.2025;[Epub] CrossRef - Worsening of health disparities across COVID-19 pandemic stages in Korea
Hyejin Lee, Hyunwoo Nam, Jae-ryun Lee, Hyemin Jung, Jin Yong Lee Epidemiology and Health.2024; : e2024038. CrossRef - Trends in Regional Disparities in Cardiovascular Surgery and Mortality in Korea: A National Cross-sectional Study
Dal-Lae Jin, Kyoung-Hoon Kim, Euy Suk Chung, Seok-Jun Yoon Journal of Preventive Medicine and Public Health.2024; 57(3): 260. CrossRef - Low household income increases risks for chronic obstructive pulmonary disease in young population: a nationwide retrospective cohort study in South Korea
Chiwook Chung, Kyu Na Lee, Dong Wook Shin, Sei Won Lee, Kyungdo Han BMJ Open Respiratory Research.2024; 11(1): e002444. CrossRef
- Trends in the Quality of Primary Care and Acute Care in Korea From 2008 to 2020: A Cross-sectional Study
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Yeong Geun Gwon, Seung Jin Han, Kyoung Hoon Kim
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J Prev Med Public Health. 2023;56(3):248-254. Published online April 12, 2023
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DOI: https://doi.org/10.3961/jpmph.23.015
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2,234
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107
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Abstract
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- Objectives
Measuring the quality of care is paramount to inform policies for healthcare services. Nevertheless, little is known about the quality of primary care and acute care provided in Korea. This study investigated trends in the quality of primary care and acute care.
Methods Case-fatality rates and avoidable hospitalization rates were used as performance indicators to assess the quality of primary care and acute care. Admission data for the period 2008 to 2020 were extracted from the National Health Insurance Claims Database. Case-fatality rates and avoidable hospitalization rates were standardized by age and sex to adjust for patients’ characteristics over time, and significant changes in the rates were identified by joinpoint regression.
Results The average annual percent change in age-/sex-standardized case-fatality rates for acute myocardial infarction was -2.3% (95% confidence interval, -4.6 to 0.0). For hemorrhagic and ischemic stroke, the age-/sex-standardized case-fatality rates were 21.8% and 5.9%, respectively in 2020; these rates decreased since 2008 (27.1 and 8.7%, respectively). The average annual percent change in age-/sex-standardized avoidable hospitalization rates ranged from -9.4% to -3.0%, with statistically significant changes between 2008 and 2020. In 2020, the avoidable hospitalization rates decreased considerably compared with the 2019 rate because of the coronavirus disease 2019 pandemic.
Conclusions The avoidable hospitalization rates and case-fatality rates decreased overall during the past decade, but they were relatively high compared with other countries. Strengthening primary care is an essential requirement to improve patient health outcomes in the rapidly aging Korean population.
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Summary
Korean summary
본 연구에서는 급성심근경색증과 뇌졸중 치명률, 외래진료 민감질환의 예방 가능한 입원율을 사용하여 한국의 의료 질 수준을 분석하였다. 2008~2020년 동안 치명률과 예방 가능한 입원율은 감소하는 추세이다. 그러나, 예방 가능한 입원율은 다른 국가에 비해 상대적으로 높아 환자의 건강결과 향상을 위하여 일차의료 강화가 요구된다.
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Citations
Citations to this article as recorded by
- National Expenditures on Anticancer and Immunomodulating Agents During 2013–2022 in Korea
Jieun Yun, Youngs Chang, Minsol Jo, Yerin Heo, Dong-Sook Kim Journal of Korean Medical Science.2025;[Epub] CrossRef - Mortality and Disparities of Acute Myocardial Infarction and Stroke in Korea, 2008–2019
Ji-Sook Choi, Soomin Kim, Choon-Seon Park, Hyejin Lee, Jin Yong Lee, Sun Min Kim Yonsei Medical Journal.2024; 65(9): 534. CrossRef
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