OBJECTIVES: We estimated the population prevalence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including unreported infections, through a Korea Seroprevalence Study of Monitoring of SARS-CoV-2 Antibody Retention and Transmission (K-SEROSMART) in 258 communities throughout Korea. METHODS: In August 2022, a survey was conducted among 10,000 household members aged 5 years and older, in households selected through two stage probability random sampling. During face-to-face household interviews, participants self-reported their health status, COVID-19 diagnosis and vaccination history, and general characteristics. Subsequently, participants visited a community health center or medical clinic for blood sampling. Blood samples were analyzed for the presence of antibodies to spike proteins (anti-S) and antibodies to nucleocapsid proteins (anti-N) SARS-CoV-2 proteins using an electrochemiluminescence immunoassay. To estimate the population prevalence, the PROC SURVEYMEANS statistical procedure was employed, with weighting to reflect demographic data from July 2022. RESULTS: In total, 9,945 individuals from 5,041 households were surveyed across 258 communities, representing all basic local governments in Korea. The overall population-adjusted prevalence rates of anti-S and anti-N were 97.6% and 57.1%, respectively. Since the Korea Disease Control and Prevention Agency has reported a cumulative incidence of confirmed cases of 37.8% through July 31, 2022, the proportion of unreported infections among all COVID-19 infection was suggested to be 33.9%. CONCLUSIONS The K-SEROSMART represents the first nationwide, community-based seroepidemiologic survey of COVID-19, confirming that most individuals possess antibodies to SARS-CoV-2 and that a significant number of unreported cases existed. Furthermore, this study lays the foundation for a surveillance system to continuously monitor transmission at the community level and the response to COVID-19.

Patients on dialysis have numerous gastrointestinal problems related to uremia, which may represent concealed cholecystitis. We investigated the incidence and risk of acute cholecystitis in dialysis patients and used national health insurance data to identify acute cholecystitis in Korea. Methods: The Korean National Health Insurance Database was used, with excerpted data from the insurance claim of the International Classification of Diseases code of dialysis and acute cholecystitis treated with cholecystectomy. We included all patients who commenced dialysis between 2004 and 2013 and selected the same number of controls via propensity score matching. Results: A total of 59,999 dialysis and control patients were analyzed; of these, 3,940 dialysis patients (6.6%) and 647 controls (1.1%) developed acute cholecystitis. The overall incidence of acute cholecystitis was 8.04-fold higher in dialysis patients than in controls (95% confidence interval, 7.40–8.76). The acute cholecystitis incidence rate (incidence rate ratio, 23.13) was especially high in the oldest group of dialysis patients (aged ≥80 years) compared with that of controls. Dialysis was a significant risk factor for acute cholecystitis (adjusted hazard ratio, 8.94; 95% confidence interval, 8.19–9.76). Acute cholecystitis developed in 3,558 of 54,103 hemodialysis patients (6.6%) and in 382 of 5,896 patients (6.5%) undergoing peritoneal dialysis. Conclusion: Patients undergoing dialysis had a higher incidence and risk of acute cholecystitis than the general population. The possibility of a gallbladder disorder developing in patients with gastrointestinal problems should be considered in the dialysis clinic.

Purpose: Ductal carcinoma In Situ (DCIS) is common in South Korea. We evaluated the patterns of axillary surgery among patients with DCIS to highlight the need for compliance with the updated national guidelines. We also evaluated whether sentinel lymph node biopsy (SLNB) was performed in accordance with the national guidelines. Methods: The Korean Health Insurance Review and Assessment Service-National Inpatient Sample database was searched for patients with DCIS (2009–2015) to identify axillary surgery patterns by breast surgery type, year of diagnosis, age at diagnosis, and the location and volume of surgeries for DCIS at the hospital. The rates of SLNB and axillary dissection were compared using descriptive statistics and univariate analyses. Analyses were also conducted using the chi-squared test and multiple logistic regression analysis. Results: We identified 16,315 Korean women who underwent surgery for DCIS, including 11,292 cases of SLNB (69.2%) and 131 cases of axillary lymph node dissection (0.8%).Breast-conserving surgery (BCS) was performed in 10,323 patients (63.3%) with an SLNB rate of 56.0%, while total mastectomy (TM) was performed in 5,992 patients (36.7%), with an SLNB rate of 92.0%. During 2009–2015, the SLNB rate during TM increased from 88.23% to 92.80%. SLNB was influenced by hospital region and surgical volume, and hospitals performing low volumes of surgeries were significantly more likely to perform SLNB regardless of the surgery type (odds ratio, 1.372; 95% confidence interval, 1.265–1.488). Conclusion Although the Korean guidelines recommend SLNB for all TM procedures and select BCS procedures for DCIS, relatively high rates of SLNB were performed for BCS, and there was inter-hospital variability in performing SLNB. Improved compliance with the guidelines by the surgeons is critical for Korean patients with DCIS.

Background: We investigated the incidence and risk of retinal vein occlusion (RVO) in endstage renal disease (ESRD) patients on dialysis in Korea. Methods: In this nationwide cohort study, we used Korean National Health Insurance Service data between 2004 and 2013 for analysis. ESRD patients who started dialysis from 2004 to 2013 and an equal number of controls were selected through propensity score matching. RVO incidence in both cohorts were calculated for 2004–2013 using washout data from 2003. The multivariable Cox proportional hazards model was used to assess the risk of RVO in dialysis cohort. The Kaplan-Meier method was used to generate the cumulative RVO incidence curve.Whether the dialysis modality affects the development of RVO was also evaluated. Results: In this study, 74,551 ESRD patients on dialysis and the same number of controls were included. The incidence of RVO was significantly higher in the dialysis cohort than in the control cohort (dialysis = 7.3/1,000 person-years [PY]; control = 1.9/1,000 PY; P < 0.001). The cumulative-incidence of RVO was also significantly higher in the dialysis cohort than in the control cohort (P < 0.001; log-rank test). However, there was no significant difference in the incidence of RVO between the two dialysis methods (P = 0.550; log-rank test). Conclusion This study provided epidemiological evidence that receiving dialysis for ESRD could increase the risk of developing RVO. We also found a rapid increase in the incidence of RVO with a longer dialysis period. These results strengthen the relationship between retinal vascular disease and renal function.

Purpose: Ductal carcinoma In Situ (DCIS) is common in South Korea. We evaluated the patterns of axillary surgery among patients with DCIS to highlight the need for compliance with the updated national guidelines. We also evaluated whether sentinel lymph node biopsy (SLNB) was performed in accordance with the national guidelines. Methods: The Korean Health Insurance Review and Assessment Service-National Inpatient Sample database was searched for patients with DCIS (2009–2015) to identify axillary surgery patterns by breast surgery type, year of diagnosis, age at diagnosis, and the location and volume of surgeries for DCIS at the hospital. The rates of SLNB and axillary dissection were compared using descriptive statistics and univariate analyses. Analyses were also conducted using the chi-squared test and multiple logistic regression analysis. Results: We identified 16,315 Korean women who underwent surgery for DCIS, including 11,292 cases of SLNB (69.2%) and 131 cases of axillary lymph node dissection (0.8%).Breast-conserving surgery (BCS) was performed in 10,323 patients (63.3%) with an SLNB rate of 56.0%, while total mastectomy (TM) was performed in 5,992 patients (36.7%), with an SLNB rate of 92.0%. During 2009–2015, the SLNB rate during TM increased from 88.23% to 92.80%. SLNB was influenced by hospital region and surgical volume, and hospitals performing low volumes of surgeries were significantly more likely to perform SLNB regardless of the surgery type (odds ratio, 1.372; 95% confidence interval, 1.265–1.488). Conclusion Although the Korean guidelines recommend SLNB for all TM procedures and select BCS procedures for DCIS, relatively high rates of SLNB were performed for BCS, and there was inter-hospital variability in performing SLNB. Improved compliance with the guidelines by the surgeons is critical for Korean patients with DCIS.

Background: We investigated the incidence and risk of retinal vein occlusion (RVO) in endstage renal disease (ESRD) patients on dialysis in Korea. Methods: In this nationwide cohort study, we used Korean National Health Insurance Service data between 2004 and 2013 for analysis. ESRD patients who started dialysis from 2004 to 2013 and an equal number of controls were selected through propensity score matching. RVO incidence in both cohorts were calculated for 2004–2013 using washout data from 2003. The multivariable Cox proportional hazards model was used to assess the risk of RVO in dialysis cohort. The Kaplan-Meier method was used to generate the cumulative RVO incidence curve.Whether the dialysis modality affects the development of RVO was also evaluated. Results: In this study, 74,551 ESRD patients on dialysis and the same number of controls were included. The incidence of RVO was significantly higher in the dialysis cohort than in the control cohort (dialysis = 7.3/1,000 person-years [PY]; control = 1.9/1,000 PY; P < 0.001). The cumulative-incidence of RVO was also significantly higher in the dialysis cohort than in the control cohort (P < 0.001; log-rank test). However, there was no significant difference in the incidence of RVO between the two dialysis methods (P = 0.550; log-rank test). Conclusion This study provided epidemiological evidence that receiving dialysis for ESRD could increase the risk of developing RVO. We also found a rapid increase in the incidence of RVO with a longer dialysis period. These results strengthen the relationship between retinal vascular disease and renal function.

BACKGROUND: The numbers of patients on dialysis and their life expectancies are increasing. Reduced renal function is associated with an increased risk of cancer, but the cancer incidence and sites in dialysis patients compared with those of the general population require further investigation. We investigated the incidences of various cancers in dialysis patients in Korea and used national health insurance data to identify cancers that should be screened in dialysis clinics. METHODS: We accessed the Korean National Health Insurance Database and excerpted data using the International Classification of Disease codes for dialysis and malignancies. We included all patients who commenced dialysis between 2004 and 2013 and selected the same number of controls via propensity score matching. RESULTS: A total of 48,315 dialysis patients and controls were evaluated; of these, 2,504 (5.2%) dialysis patients and 2,201 (4.6%) controls developed cancer. The overall cancer risk was 1.54-fold higher in dialysis patients than in controls (adjusted hazard ratio, 1.71; 95% confidence interval, 1.61–1.81). The cancer incidence rate (incidence rate ratio [IRR], 3.27) was especially high in younger dialysis patients (aged 0–29 years). The most common malignancy of end-stage renal disease patients and controls was colorectal cancer. The major primary cancer sites in dialysis patients were liver and stomach, followed by the lung, kidney, and urinary tract. Kidney cancer exhibited the highest IRR (6.75), followed by upper urinary tract (4.00) and skin cancer (3.38). The rates of prostate cancer (0.54) and oropharyngeal cancer (0.72) were lower than those in the general population. CONCLUSION: Dialysis patients exhibited a higher incidence of malignancy than controls. Dialysis patients should be screened in terms of colorectal, liver, lung, kidney and urinary tract malignancies in dialysis clinics.
Colorectal Neoplasms ; Dialysis ; Epidemiology ; Humans ; Incidence ; International Classification of Diseases ; Kidney ; Kidney Failure, Chronic ; Kidney Neoplasms ; Korea ; Life Expectancy ; Liver ; Lung ; National Health Programs ; Oropharyngeal Neoplasms ; Propensity Score ; Prostatic Neoplasms ; Renal Dialysis ; Skin Neoplasms ; Stomach ; Urinary Tract

BACKGROUND: Chemoprophylaxis has been used to prevent malaria among soldiers and secondary transmission, as it effectively facilitates a decline in disease occurrence and secondary prevention. However, poor compliance and decreased risk of exposure to malaria necessitate that control strategies be reestablished. METHODS: To predict the incidence of malaria according to a control strategy, we proposed a mathematical model for its transmission using epidemiological data from 2010 to 2012. The benefit component included in the analyses was the averted cost with each control strategy, and the cost components were the cost of implementing chemoprophylaxis and early diagnosis. RESULTS: The chemoprophylaxis regimen with hydroxychloroquine sulfate and primaquine was Intervention 1, the regimen with primaquine only was Intervention 2, and diagnosis with a rapid diagnostic test (RDT) kit within 5 days of fever was Intervention 3. The simulation indicated that the combined control program with chemoprophylaxis and early diagnosis would be the most effective strategy, whereas sole early diagnosis would be the least effective strategy. However, the cost-benefit ratio of chemoprophylaxis was less than Intervention 1, irrespective of the varying range of chemoprophylaxis compliance, and that of early diagnosis was more than Intervention 1, regardless of the varying early diagnosis rate and demand for the RDT kit. Although chemoprophylaxis would be more effective at reducing the incidence of malaria than early diagnosis, it is less economical due to the higher cost. CONCLUSION: Our results support the introduction of early diagnosis with a RDT kit to control malaria in the Republic of Korea Army.
Chemoprevention* ; Compliance ; Cost-Benefit Analysis* ; Diagnosis ; Diagnostic Tests, Routine ; Early Diagnosis* ; Fever ; Humans ; Hydroxychloroquine ; Incidence ; Malaria* ; Military Personnel* ; Models, Theoretical ; Primaquine ; Republic of Korea ; Secondary Prevention

BACKGROUND: The converging epidemics of tuberculosis (TB) and end-stage renal disease (ESRD) have generated a significant public health burden, however, previous studies have been limited to a small number of patients. This nationwide cohort study aimed to assess the rate of developing active TB among patients receiving dialysis for ESRD. METHODS: The Korean national health insurance database was used to identify patients receiving dialysis for new-onset ESRD during 2004–2013, who were propensity score matched to an equivalent number of non-dialysis subjects from the general population. The incidences of active TB in the ESRD and control cohorts were calculated for 2004–2013, and multivariable Cox proportional hazards model was used to evaluate the ESRD-related risk of active TB. RESULTS: During 2004–2013, 59,584 patients received dialysis for newly diagnosed ESRD. In the dialysis and control cohorts, 457 (0.8%) and 125 (0.2%) cases of active TB were detected, respectively. Patients with ESRD were associated with a significantly higher risk of active TB compared to the controls (incidence rate ratio, 4.80). The ESRD cohort had an independently elevated risk of active TB (adjusted hazard ratio, 4.39; 95% confidence interval, 3.60–5.37). CONCLUSION: We found that patients receiving dialysis for ESRD had an elevated risk of active TB. These results highlight the need for detailed and well-organised guidelines for active TB screening among patients with ESRD.
Cohort Studies* ; Dialysis ; Humans ; Incidence ; Kidney Failure, Chronic* ; Korea ; Mass Screening ; National Health Programs ; Propensity Score ; Proportional Hazards Models ; Public Health ; Renal Insufficiency, Chronic ; Tuberculosis*

BACKGROUND: This study was conducted to analyze the influence of socioeconomic characteristics of community on the food insecurity under the control of personal socioeconomic factors which may be influence to the food security. METHODS: Food insecurity and individual socioeconomic characteristics were obtained from 2012 community health survey. Socioeconomic characteristics of communities were extracted from the data of Statistics Korea and local governments. Personal socioeconomic factors were sex, age, educational status, job, and monthly family income. Socioeconomic characteristics of communities were administrative district (urban vs. rural), senior population rate, degree of financial self reliance, degree of financial independence, portion of welfare budget, number of welfare facilities, and unemployment rate. We analysed the relationships between the food insecurity and socioeconomic characteristics of community using multi-level analysis under the control of personal characteristics. RESULTS: On personal level age, sex, education status, and monthly family income were related with food insecurity. On community level administrative district (urban vs. rural), degree of financial independence, unemployment rate, and proportion of welfare budget among local general government accounts were related to individual food insecurity. Rural area, district with low levels of financial independence, low portion of welfare budget, and greater unemployment rate showed a higher level of food insecurity. CONCLUSION: To reduce the level of food insecurity in a community it is necessary to decrease the unemployment rate, in addition to providing support from the central government by increasing the proportion of the welfare budget so that both factors contribute to raising the degree of financial independence.
Adult* ; Budgets ; Education ; Educational Status ; Food Supply* ; Health Surveys ; Humans ; Korea ; Socioeconomic Factors ; Unemployment