Epidemiology and Health最新文献

Objectives: This study aimed to evaluate a fixed-duration algorithm for gestational age (GA) estimation according to pregnancy outcomes and to describe the GA distribution of pregnancy-related codes in Korea.

Methods: We included 351,055 pregnancy episodes (2019-2022) from linked data between the National Health Insurance Service and the Korea Immunization Registry (KIRIS). GA from claims data was estimated by subtracting fixed durations from the delivery date (algorithm-based GA), and GA derived from KIRIS was defined as the gold standard. Accuracy was evaluated as the proportion of episodes in which the difference between the estimated GA and the reference standard fell within ±2 weeks. We described the distributions of the GA at which each prenatal test, pregnancy complication, and diagnostic code was recorded.

Results: Algorithm-based GA estimation showed high accuracy for live births (92.2% within ±2 weeks) but markedly lower accuracy for non-live-birth outcomes, including stillbirth (3.3%), termination (7.2%), spontaneous abortion (45.2%), and ectopic pregnancy (20.0%). In additional analyses aimed at identifying potential indicators for improving GA estimation, most events occurred within clinically expected timeframes, although some individual codes exhibited poor temporal alignment.

Conclusion: Algorithm-based GA estimation using claims data performed well for live births but demonstrated limited accuracy for non-live-birth outcomes. Incorporating information from prenatal tests and pregnancy complications may enhance GA estimation.

Confounding and the healthy worker survivor effect (HWSE) represent major methodological challenges in epidemiology, particularly in studies of low-dose exposures, where effect sizes are small and risk estimates can be readily distorted by bias. This systematic review aimed to summarize the methods used to adjust for confounding and the HWSE in studies of medical radiation workers. We systematically searched PubMed and Embase for studies of medical radiation workers from inception through June 30, 2025. Studies reporting excess risk estimates for any health outcomes associated with occupational radiation exposure were included. Study selection followed the PECO criteria, and data were synthesized descriptively. The review was conducted in accordance with the PRISMA guidelines and was registered in PROSPERO (CRD42024589851). Sixteen eligible studies from 3 countries were identified, all of which were rated as high quality. To control for confounding, regression was used in all studies, followed by stratification (62.5%) and restriction (18.8%). Age, sex, and birth year were adjusted for in all models, with smoking being the next most frequently controlled variable. To mitigate the HWSE, only a single approach, adjustment for employment characteristics, was identified, and it was applied in 3 studies (18.8%). No other approaches, including restriction or g-methods were employed. Although confounding is generally addressed using conventional analytical approaches, the HWSE has rarely been considered in studies of medical radiation workers. More comprehensive strategies that explicitly account for the HWSE are needed to improve the validity of risk estimates, particularly in low-dose occupational studies.

Objectives: Chronic inflammation has been implicated in the development of hypertension in numerous previous studies. However, evidence regarding the association between hematological inflammatory indices derived from complete blood count tests and the long-term risk of hypertension remains limited. Therefore, this study aimed to investigate the association between various hematological inflammatory indices and the risk of incident hypertension in a large cohort study.

Methods: We analyzed data from a large Korean cohort (n = 128,241). The incident risk of hypertension was evaluated according to quartiles of the neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII), and systemic inflammatory response index (SIRI) using Cox proportional hazards models. Additional analyses were conducted for high-sensitivity C-reactive protein (hsCRP) levels and stratified by sex.

Results: During a median follow-up of 6.8 years, 18,686 participants (14.5%) developed hypertension. Higher quartiles of SII, SIRI, and NLR were significantly associated with an increased risk of incident hypertension in both sexes. PLR showed a clearer positive association in women, whereas MLR demonstrated only marginal associations. These patterns were consistent with the associations observed for hsCRP.

Conclusion: These findings suggest that elevated hematological inflammatory indices above certain thresholds are associated with an increased risk of hypertension, even among young and generally healthy individuals.

Objectives: The COVID-19 pandemic had direct effects on population health through infection and morbidity, as well as indirect effects on population mental health. We estimated the network structure of post-traumatic stress symptoms (PTSS) and depressive symptoms throughout the pandemic in South Korea and aimed to identify the most central and bridging symptoms.

Methods: Participants aged 30-64 years completed mental health surveys across 3 phases of the COVID-19 pandemic: March 2020 (N=1,925), February-March 2021 (N=1,754), and December 2021-January 2022 (N=1,595). Using PTSS and depressive symptom data, we conducted network analyses, and the primary measures of symptom importance (centrality) were expected influence and bridge expected influence.

Results: In the comorbidity network, although the most central symptoms fluctuated over the course of the pandemic, sleep problems were consistently identified as the most influential bridge symptoms throughout. The symptom network structure differed between the subacute and chronic phases of the pandemic.

Conclusion: We found evidence of changes in the network structure of PTSS and depressive symptoms, even as sleep problems retained a consistent role as a bridging symptom. Although overall network structures varied across phases of the pandemic, the bridging role of sleep-related symptoms remained consistently strong, suggesting that sleep problems may represent a general and enduring mechanism underlying PTSS-depression comorbidity. During future pandemics, prompt screening for sleep problems may help prevent the development of comorbidity between PTSS and depressive symptoms.

Objectives: This study examined whether individuals with consistently normal liver enzyme levels are protected from alcohol-related liver disease and investigated whether heavy drinking increases liver disease risk independent of normal biomarker status.

Methods: We conducted a nationwide cohort study using Korean National Health Insurance Service data (2002-2019), including 19,035 participants aged ≥40 years who maintained normal liver enzyme levels (AST ≤40 U/L, ALT ≤40 U/L, GGT ≤63 U/L for men and ≤35 U/L for women) across multiple examinations conducted between 2002 and 2008. Participants were categorized as abstainers (≤1 time/month), moderate drinkers (≤2 times/week), and heavy drinkers (≥3 times/week). Primary outcomes included incident liver disease identified using diagnostic codes. Cox proportional hazards models were used to estimate hazard ratios (HRs), with age-stratified analyses performed.

Results: Heavy drinkers demonstrated a significantly higher risk of liver disease than abstainers (HR, 1.733; 95% CI, 1.403-2.141), whereas moderate drinkers showed no significant association (HR, 1.060; 95% CI, 0.945-1.188). Consistent patterns emerged for middle-aged adults (40-69 years), with attenuated effects among participants aged ≥70 years. When alcoholic liver disease was analyzed specifically, both moderate (HR, 1.286; 95% CI, 1.046-1.580) and heavy drinkers (HR, 2.859; 95% CI, 2.092-3.907) exhibited significantly increased hazards.

Conclusion: Despite normal liver enzyme levels, heavy alcohol consumption was associated with a significantly increased risk of liver disease. These findings challenge current reactive screening paradigms relying solely on biomarker abnormalities and support proactive alcohol counseling regardless of enzyme results More sensitive strategies are needed for early detection of alcohol-related liver injury.

Varicella, caused by the varicella-zoster virus (VZV), was once nearly universal in childhood before the advent of vaccination and may lead to severe complications and even fatalities. Monitoring varicella vaccine effectiveness is crucial yet often overlooked in settings with limited surveillance infrastructure. The Korean Varicella Immunization Monitoring (K-VIM) Scheme was established to address this gap by assembling a national, insurance-based birth cohort of children born between 2011 and 2022 (N = 4,505,165). This cohort leverages comprehensive healthcare databases in the Republic of Korea to capture vaccination records, medical visits, and varicella infection outcomes for virtually all children within the target birth years. We describe the enrollment and key characteristics of the K-VIM cohort, including vaccination coverage, demographic features, and varicella incidence to date. The structure and completeness of Korea's national health insurance and immunization registries enable robust longitudinal tracking of varicella infections among vaccinated versus unvaccinated children. Early findings demonstrate distinct patterns in infection rates and disease severity according to vaccination status. The K-VIM Scheme provides a foundation for ongoing epidemiological studies of varicella vaccine effectiveness and public health impact in Korea. Future plans include evaluating the long-term effects of varicella vaccination, including potential impacts on herpes zoster incidence, using diverse study designs to strengthen causal inference and inform immunization policy.

Objectives: Kudoa septempunctata has been identified as the causative agent of food poisoning following the consumption of raw farmed Paralichthys olivaceus. However, cohort studies providing robust evidence for an association between K. septempunctata and gastrointestinal symptoms remain limited. This prospective cohort study investigated the association between the consumption of K. septempunctata-infected farmed P. olivaceus and the occurrence of gastrointestinal symptoms.

Methods: Individuals who purchased raw farmed P. olivaceus between 2020 and 2021 were selected as the study population. Study data included 2 rounds of questionnaire surveys administered before and after consumption, 2 muscle specimens obtained from each purchased fish, and human biological specimens collected from individuals who developed gastrointestinal symptoms within 24 hours after consumption. Data were analyzed using the chi-square test and t-test, and the association between consumption of K. septempunctata-infected farmed P. olivaceus and gastrointestinal symptoms was evaluated using relative risk estimates between exposure groups.

Results: The relative risk of gastrointestinal symptoms associated with exposure to K. septempunctata-infected P. olivaceus ranged from 71.2 (95% CI, 27.0-178.6) to 124.5 (95% CI, 43.5-355) across the 2 case definitions. A strong and statistically significant association was observed between exposure to K. septempunctata-infected P. olivaceus and the development of acute gastrointestinal symptoms.

Conclusion: These findings indicate both an association and a causal relationship between consumption of K. septempunctata-infected farmed P. olivaceus and the onset of gastrointestinal symptoms.

Objectives: We evaluated the associations of smoking status, intensity, duration, and cumulative exposure with the risk of dental implant failure in Korean adults.

Methods: This retrospective cohort study utilized the National Health Insurance Service-Health Screening Cohort (2016-2019). Overall, 23,573 individuals who had completed the dental implant process were included. Smoking status was categorized as non-smoker, ex-smoker, or current smoker. Smoking intensity, duration, and cumulative exposure were classified using standardized thresholds (>10 cigarettes per day, >10 years, and >10 pack-years). Implant failure was defined as reimplantation or removal. Cox proportional hazards models were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs), adjusting for demographic, clinical, and behavioral covariates.

Results: During follow-up, 605 implant failures occurred: 344 in non-smokers, 182 in ex-smokers, and 79 in current smokers. The corresponding incidence rates per 1,000 person-years were 11.6, 16.5, and 22.3, respectively. Current smoking was significantly associated with higher implant failure risk (adjusted HR, 1.59; 95% CI, 1.20 to 2.09), while ex-smokers displayed a non-significant increase (adjusted HR, 1.16; 95% CI, 0.94 to 1.45). A dose-response relationship was observed: smoking more than 10 cigarettes per day, smoking for more than 10 years, or exceeding 10 pack-years was associated with significantly increased risk.

Conclusion: Smoking is a significant, dose-dependent risk factor for dental implant failure in Korean adults. Current smokers have the highest risk; smoking cessation may reduce adverse outcomes. These findings emphasize the importance of detailed smoking assessments and cessation counseling in implant care and public health strategies.

The Korea National Health and Nutrition Examination Survey (KNHANES) is a national health survey mandated by Article 16 of the National Health Promotion Act to assess the health and nutritional status of the Korean population. Over the past 2 decades, the survey has continuously introduced timely survey components while strengthening its survey methodology and operational systems to enhance both the policy relevance and scientific utility of its findings. The 10th KNHANES (2025-2027) preserves the statistical representativeness of its sampling design while expanding the use of web-based self-administered questionnaires to improve participant convenience. In response to Korea's transition into a super-aged society, the 10th KNHANES incorporates enhanced older-adult health surveys, including osteoporosis assessment and older adults' life functioning, and newly introduces items addressing social support as part of the social determinants of health. In addition, a longitudinal follow-up survey system has been established to monitor long-term changes in population health. Collectively, these changes are expected to improve understanding of aging-related health issues, support evidence-based national health policy development, and expand the applicability of KNHANES data for academic research.

The increasing number of people living with human immunodeficiency virus (HIV) in Korea has prompted interest in using the national surveillance system as a database for studying their health. To investigate the relationships between socio-demographic and epidemiological characteristics and mortality rates, a nationwide retrospective cohort was formed by integrating surveillance data with the Cause of Death Statistics from Statistics Korea. This integration included incidence reports, epidemiological investigations, and death reports from the surveillance data, enriched with detailed mortality information from the Cause of Death data. The cohort comprised 17,199 adult Korean individuals diagnosed with HIV infection from 1985 to 2020. By the end of 2020, 2,721 of these individuals were confirmed deceased. The sex ratio of the study participants was 14.3:1.0 (male to female), with 78.2% being under 50 years old at the time of diagnosis. Sexual contact was identified as the primary transmission route, accounting for 75.7% of cases. HIV disease emerged as the predominant cause of death, representing two-thirds (1,817 of 2,721) of the fatalities, followed by injuries and trauma, malignancies, and cardiovascular diseases. Recommendations for further cohort studies may be submitted to the Korea Disease Control and Prevention Agency.