Health Insurance Review and Assessment Service

Sex disparities in stroke outcomes are well-recognized, but it remains unclear whether these disparities vary across stroke subtypes and how they relate to differences in acute care delivery. The aim of the study was to examine sex differences in long-term mortality, functional outcomes, and acute stroke management across stroke subtypes using a nationwide population-based cohort. This retrospective cohort study analyzed linked clinical audit and claims data from 58,429 patients with acute stroke admitted to 269 hospitals in South Korea between 2018 and 2021. Clinical data were derived from the national Acute Stroke Quality Assessment Program and linked to claims. The primary outcome was all-cause mortality. The secondary outcome was poor functional outcome at discharge. Multivariable Cox and logistic regression models were used to assess associations between sex and outcomes, stratified by stroke subtype and adjusted for age, stroke severity, and comorbidities. Differences in acute stroke care were also analyzed. Of 58,429 patients (mean [SD] age, 68.6 [13.8] years; 43.9% female), 76.1% had ischemic stroke (IS), 15.7% intracerebral hemorrhage (ICH), and 8.2% subarachnoid hemorrhage (SAH). Females were older than males across all subtypes and had different comorbidity profiles. After adjustment, females had significantly lower mortality in all subtypes (adjusted hazard ratios [95% CI]: IS, 0.77 [0.74-0.80]; ICH, 0.60 [0.56-0.64]; SAH, 0.60 [0.54-0.67]; all P < 0.001). Functional outcomes varied: females had worse outcomes in IS, better in ICH, and no difference in SAH. Males were more likely to receive reperfusion and surgical therapies; females were more likely to receive rehabilitation services. These care differences did not fully explain the observed disparities in outcomes. In this national cohort, sex disparities in stroke outcomes differed by subtype. Despite lower adjusted mortality in females, functional outcomes were not uniformly better. These findings underscore the importance of adopting sex- and subtype-specific approaches to stroke care, secondary prevention, and rehabilitation.

Abstract The Health Insurance Review and Assessment Service Korean Nationwide Claims OMOP-CDM database (HIRA K-OMOP) is a nationwide data resource formatted according to the Observational Medical Outcomes Partnership (OMOP) Common Data Model (CDM) and derived from South Korea’s National Health Insurance claims data. It includes patient-level information and insurance claims for the entire population of South Korea from 2015 to 2024, providing population-scale coverage (56,416,773 patients). The HIRA K-OMOP database captures comprehensive data generated under the National Health Insurance program, including diagnoses, medications (inpatient and outpatient prescriptions and pharmacy dispensing records), procedures, and claim costs. This enables high-resolution observation of healthcare utilization and clinical practice among the Korean population. The database was constructed by mapping Korean Electronic Data Interchange (EDI) codes to OMOP standard concepts. The requisite mapping tables were developed by the investigators of the “Integrating Local Vocabulary into OMOP CDM” study and released in June 2025, allowing nationally generated claims data to be transformed into an analysis-ready research resource. The complete analytic vocabulary set underpinning the build was obtained from the official OHDSI ATHENA portal ( athena.ohdsi.org ) in March 2025. Key strengths of the database include deterministic linkage to the national death registry and the explicit separation of prescribing and dispensing records, which enhances the validity of drug exposure assessments. The database is accessible to researchers through a privacy-preserving distributed research environment managed by HIRA. Key Features The Health Insurance Review and Assessment Service Korean Nationwide Claims OMOP-CDM database ( HIRA K-OMOP ) is a nationwide data resource formatted according to the Observational Medical Outcomes Partnership (OMOP) Common Data Model (CDM) and derived from South Korea’s national health insurance claims data. 1,2 It includes patient-level information and insurance claims for the entire population of South Korea from 2015 to 2024, providing population-scale coverage (56,416,773 patients). The HIRA K-OMOP database includes comprehensive data recorded as part of the National Health Insurance program, encompassing diagnosis, medications (inpatient, outpatient prescriptions, and dispensing records), procedure and claim costs. This allows for high-resolution observation of healthcare utilization and clinical practice among the Korean population. 3,4 It was constructed by mapping Korean Electronic Data Interchange (EDI) codes to OMOP standard concepts (concept IDs). The requisite mapping tables were developed by the investigators of the “Integrating Local Vocabulary into OMOP CDM” study and released in June 2025. 5 Consequently, nationally generated claims data have been transformed into an analysis-ready research resource. The complete analytic vocabulary set, which underpins the build, was obtained from the official OHDSI ATHENA portal ( athena.ohdsi.org ) in March 2025. 6

ObjectiveInformation regarding the use of antibiotics in long-term care hospitals (LCHs) during COVID-19 remains limited. The aim of the study was to examine the antibiotics use in Korean LCHs during the COVID-19 pandemic period.MethodsWe conducted a nationwide cohort study between 2020 and 2023. During this period, a total of 1,835,398 patients were admitted to 1,829 LCHs.Results1,043,346 (56.9%) received antibiotics. The overall antibiotic use in LCHs was 133.33 days of therapy (DOT) per patient-days (PDs), which was lower than that observed in tertiary (933.89), secondary (798.26), and primary care hospitals (566.77). In contrast, the intensity of antibiotic use among treated patients was highest in LCHs (40.01 DOT), exceeding that in tertiary (15.22), secondary (14.60), and primary care hospitals (11.74). Antibiotic use in LCHs steadily rose from 116.18 in January 2020 to 160.65 DOT per 1000 PDs in December 2023, with a notable increase during surge of COVID-19 cases. Segmented regression analysis showed a sustained increase in antibiotic use before the Omicron wave that persisted afterward. Most statistically significant increases were observed in the use of broad-spectrum antibiotics: fourth-generation cephalosporins increased by 348.0%, carbapenems by 114.6%, and glycopeptides by 92.5%.ConclusionsDuring the COVID-19 pandemic, we found a significant increasing trend in antibiotic use, particularly in broad-spectrum antibiotics. These findings highlight the deed for strengthened antibiotic stewardship in LCHs during public health crises.Clinical trial registrationClinical trial number: Not applicable.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12879-025-12060-5.

BackgroundClinics and hospitals in South Korea are often perceived as competitors to each other. This study examines the overlapping roles in providing primary care provision between clinics and hospitals by analyzing the healthcare facility type where patients first receive diagnoses of hypertension (HTN) or diabetes mellitus (DM). We also explore the characteristics of patients that influence their choice of healthcare facility and compare healthcare utilization patterns in the first year post-diagnosis by facility type.MethodsUsing 2021 claims data from the Health Insurance Review and Assessment Service, we included data from 599,955 patients with newly diagnosed HTN and 195,668 patients with newly diagnosed DM. We analyzed the distribution of new diagnoses by facility type, characteristics of patients who chose hospitals, average number of facility visits and medical expenses in the first year following the initial diagnosis, and continuity of care index.ResultsAmong the newly diagnosed patients, 82.5% of HTN and 66.6% of DM cases were diagnosed in clinics, whereas 17.5% and 33.4%, respectively, occurred in hospitals. Younger patients, those with comorbidities, and those residing outside Seoul were more likely to receive care at hospitals. Compared to those diagnosed in hospitals, patients diagnosed in clinics visited healthcare facilities more frequently and incurred greater total medical expenses but demonstrated higher continuity of care.ConclusionThese findings indicate that both clinics and hospital-level healthcare facilities, excluding general hospitals, play significant roles in providing primary care. Strengthening the clinic-based primary care system and ensuring the quality of primary care provided by hospitals are crucial. Policies that promote transparency in the quality assessments of healthcare facilities can help patients make informed decisions when choosing between clinics and hospitals.

Background: Although erythropoiesis-stimulating agent (ESA) therapy is fundamental for correcting anemia, excessive ESA administration is associated with increased risks. This study aimed to investigate the impact of the erythropoietin resistance index (ERI) on clinical outcomes in a population-based cohort of hemodialysis (HD) patients. Methods: This retrospective study analyzed datasets from patients who underwent periodic HD quality assessments and their claims data. Overall, we included 35,913 patients. Participants were divided into quartiles based on the ERI during the 6-month assessment period: Q1, Q2, Q3, and Q4 groups. Results: The 5-year survival rates were 68.8% (Q1), 67.8% (Q2), 66.9% (Q3), and 60.2% (Q4) (p < 0.001). Multivariable analysis showed the same trends as the univariable analysis. Additionally, a spline curve using the multivariable model indicated that the increased ERI was linked to all-cause mortality. However, cardiovascular events were not associated with ERI quartiles in Cox regression analyses. Subgroup analysis revealed that in most subgroups, the all-cause mortality was significantly higher in those with a high ERI than in those with a low ERI. Further analysis using the balanced cohort, which attenuated baseline characteristic differences, confirmed that the high mortality in those with a high ERI was maintained. Conclusions: Our population-based cohort study reveals an association between the ERI and all-cause mortality in HD patients.

BackgroundThe global population of older adults is increasing, and late-life depression is becoming a significant issue. A strong relationship with one’s children is a potential factor in alleviating the risk of late-life depression. This study explored the importance of parent–child relationships, including contact, meetings, and financial support, and examined their association with depressive symptoms in older parents.MethodsData were collected from 4,476 participants who completed the Center for Epidemiological Studies Depression Scale- 10 items (CES-D 10) questionnaire from the Korean Longitudinal Study of Aging (2006–2020). Mixed-effects logistic regression analysis was conducted to evaluate the impact of parent–child relationships over time on depressive symptoms, while accounting for individual differences.ResultsAn active change in the parent–child relationship status (no → yes) was associated with lower depressive symptoms (men: odds ratio [OR] = 0.63, 95% confidence interval [CI] = 0.47–0.83; women: OR = 0.67, 95% CI = 0.51–0.88) than no change in relationship (no → no). Maintaining monthly contact (men: OR = 0.61, 95% CI = 0.47–0.78; women: OR = 0.64, 95% CI = 0.50–0.81), meeting 2–6 times per year (men: OR = 0.73, 95% CI = 0.56–0.95; women: OR = 0.76, 95% CI = 0.60–0.97), and financial support (men: OR = 0.70, 95% CI = 0.54–0.92; women: OR = 0.73, 95% CI = 0.57–0.93) were each associated with reduced parental depression.ConclusionsAmong older parents, a transition toward a more active parent–child relationship was associated with reduced depressive symptoms. Therefore, promoting parent–child relationships must be considered an important component of mental health interventions.

Stroke, a leading global cause of death, poses a substantial health burden. The incidence of stroke is high in an aging society. Appropriate healthcare resources are crucial for providing prompt interventions to patients with stroke. We investigated the factors associated with the choice between conservative and interventional treatments, including an analysis of the number of neurosurgeons required for interventional care, for patients with acute stroke. We utilized health insurance claims data from hospitals submitted to the Health Insurance Review and Assessment Service in 2018 and 2021. The data covered 60,661 patients with acute stroke admitted to the emergency room in tertiary or general hospitals. The number of hospital neurosurgeons was the key variable of interest; conservative and interventional treatments were the independent variables. Using a multi-level analysis, we identified the individual- and hospital-level factors associated with interventional treatment by constructing four models. The odds of patients with hemorrhage and ischemic stroke receiving intervention were 0.60 [95% confidence interval (CI), 0.31-0.52] and 0.51 [95% CI, 0.39-0.65] times lower, respectively, in the group with fewer neurosurgeons. We categorized the number of neurosurgeons and indicated an association between a minimum of three neurosurgeons and stroke treatment. We demonstrated an association between individual- and hospital-level factors and the intervention for patients with different types of stroke. We predicted the number of neurosurgeons needed for intervention. These findings can be used for the efficient distribution and utilization of healthcare resources to improve public health.

ObjectivesThis study aimed to identify patients at higher risk for regional disengagement from health services using the Patient-centered Relevance Index (P-RI).MethodsThis nationwide retrospective cohort study analyzed the relationship between the P-RI and individual patient characteristics, including medical conditions and healthcare utilization patterns. The National Health Insurance Service claims database was used to characterize healthcare utilization by 3,046,914 patients with DM from 2017 to 2020.ResultsAs compared to the mild condition group, all other groups had a lower P-RI. Significant differences were observed among the groups with P-RI lower by 16.5%, 14%, 13%, 0.4%, and 0.6% in the repeated inpatient treatment (β = -0.165, P < 0.001), complication (β = -0.141, P < 0.001), extended long-term care stay (β = -0.130, P < 0.001), comorbidity (β = -0.041, P < 0.001), and other (β = -0.058, P < 0.001) groups, respectively. Additionally, the P-RI was high among low-income and older patients with high acuity.DiscussionSouth Korea's healthcare delivery system is not regionally self-sufficient. A relatively low P-RI in the high income and younger groups indicates healthcare access inequity. Therefore, a continuous management system that ensures uniform healthcare access needs to be established.

Background Inhibitory effects of denosumab on bone remodeling are reversible and disappear once treatment is discontinued. Herein, we examined whether and to what extent delayed denosumab administration is also associated with fracture risk using nation-wide data.Methods The study cohort included women aged 45 to 89 years who were started on denosumab for osteoporosis between October 2017 and December 2019 using data from the Korean Health Insurance Review and Assessment service. Participants were stratified according to the time of their subsequent denosumab administration from the last denosumab administration, including those with within 30 days early dosing (ED30), within the planned time of 180–210 days (referent), within 30–90 days of delayed dosing (DD90), within 90–180 days of delayed dosing (DD180), and longer than 181 days of delayed dosing (DD181+). The primary outcome was the incidence of all clinical fractures.Results A total of 149,199 participants included and 2,323 all clinical fractures (including 1,223 vertebral fractures) occurred. The incidence of all fractures was significantly higher in the DD90 compared to reference group (hazard ratio [HR], 1.2; 95% confidence interval [CI], 1.1 to 1.4). The risk of all fracture was even higher in the longer delayed DD180 group (HR, 1.9; 95% CI, 1.6 to 2.3) and DD181+ group (HR, 1.8; 95% CI, 1.5 to 2.2). Increased risks of fractures with delayed dosing were consistently observed for vertebral fractures.Conclusion Delayed denosumab dosing, even by 1 to 3 months, was significantly associated with increased fracture risk. Maintaining the correct dosing schedule should be emphasized when starting denosumab.