Ajin Cho

Background: Evidence on the effectiveness of third-dose messenger RNA (mRNA) coronavirus disease 2019 (COVID-19) vaccination during the Omicron-dominant period in Asian hemodialysis (HD) patients remains limited. We evaluated the clinical effectiveness of a third mRNA vaccine dose against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, hospitalization, and mortality in Korean HD patients. Methods: Using the Korea Disease Control and Prevention Agency–National Health Insurance Service database, we conducted a nationwide cohort study of HD patients aged ≥18 years who received two or three doses of BNT162b2 or mRNA-1273 before January 16, 2022. Study outcomes were SARS-CoV-2 infection, hospitalization, and death. Cox proportional hazards models were used to assess the associations between third-dose vaccination and clinical outcomes. Results: Among 66,389 HD patients (mean age, 65.7 ± 12.9 years; 60.5% male), 55,125 (83.0%) received three vaccine doses and 11,264 (17.0%) received two doses. Receipt of three doses was associated with a significantly lower risk of SARS-CoV-2 infection (adjusted hazard ratio [aHR], 0.58; 95% confidence interval [CI], 0.56–0.60). Among 17,886 patients with SARS-CoV-2 infection, third-dose vaccine recipients had a lower risk of hospitalization (aHR, 0.65; 95% CI, 0.62–0.70) and 30-day mortality (aHR, 0.35; 95% CI, 0.30–0.41) compared with those who received two doses. Receipt of mRNA-1273 as the third dose was associated with lower observed risks of infection and hospitalization than receipt of BNT162b2. Conclusion: A third dose of an mRNA COVID-19 vaccine was associated with lower risks of SARS-CoV-2 infection, hospitalization, and mortality among HD patients during the Omicron-dominant period. These findings support the clinical importance of booster vaccination in this high-risk population.

Background: Patients with end-stage kidney disease (ESKD) frequently visit the emergency department (ED) due to complications from comorbidities and dialysis. This study aimed to investigate the clinical outcomes and patterns of ED visits, hospitalizations, and in-hospital mortality among ED visits by ESKD patients in South Korea. Methods: This study utilized data from the National Emergency Department Information System from 2019 to 2021. ED visits were analyzed for ESKD patients and compared with non-chronic kidney disease (non-CKD) patients. Logistic regression analyses were conducted to assess factors associated with hospitalization and mortality, adjusting for demographics, insurance, and clinical characteristics, including the Korean Triage and Acuity Scale (KTAS). Results: The study included 125,392 ED visits from ESKD patients and 19,287,972 from non-CKD patients. ED visits by ESKD patients had significantly higher hospitalization (66.7%) and in-hospital mortality (9.4%) rates compared to those by non-CKD patients (21.0% and 5.1%, respectively). ESKD patients were older, more frequently female, and more likely to receive medical aid. Factors strongly associated with higher hospitalization and mortality rates included advanced age, male sex, transfer from another facility, higher KTAS scores, and prolonged ED stays. Common causes of ED visits in ESKD patients included vascular device complications, digestive system disorders, pneumonia, pulmonary edema, and fluid or electrolyte imbalances. Conclusion: ED visits by patients with ESKD were characterized by high severity, hospitalization rates, and in-hospital mortality. Further research on factors affecting clinical outcomes may improve mortality and morbidity in this population.

Aims: The association between reproductive lifespan (RLS) and diabetes and metabolic syndrome in menopausal women remains unclear. We investigated whether a short RLS is associated with diabetes and metabolic syndrome using nationally representative US data. Methods: We conducted a cross-sectional analysis of menopausal women using data from the US National Health and Nutrition Examination Survey from 2007 to 2018. Weighted logistic regression models accounting for the complex survey design were used to estimate ORs and 95% CIs for diabetes and metabolic syndrome across quartiles of RLS. Results: A total of 868 postmenopausal women with a mean age of 54.1 years were included. The mean ages at menarche and menopause were 12.7 and 51.2 years, respectively. The mean RLS was 38.5 years and was categorized into quartiles (11–35, 36–39, 40–42 (reference group), and 43–50 years). Compared with the reference group, women in the second quartile had higher odds of diabetes (OR 2.23; 95% CI 1.05 to 4.73) after adjustment for age, demographic characteristics, behavioral factors, age at menarche, and family history of diabetes. In contrast, women in the shortest RLS quartile were not at increased odds of diabetes, and no significant linear trend was observed across RLS categories. No robust association was observed between RLS and metabolic syndrome. These findings were consistent in sensitivity analyses that additionally included women with surgical menopause and that further adjusted for dietary factors. Conclusion: A relatively short RLS may be associated with higher odds of diabetes, although this association did not follow a clear dose-response pattern. These findings suggest that reduced lifetime estrogen exposure may contribute to cardiometabolic risk. Given the cross-sectional design, longitudinal studies are needed to support these findings.

Clinical guidelines recommend a single-pool Kt/V (spKt/V) target of 1.2–1.4 per hemodialysis (HD) session, but optimal adequacy targets may differ by sex. We examined sex-specific associations between spKt/V and all-cause mortality in a nationwide Korean cohort of maintenance HD patients. Using data from the 2015 HD Quality Assessment and National Health Insurance Service, we included 29,349 adults on thrice-weekly HD. The association between spKt/V and mortality was estimated using Cox models, and Harrell’s C-index was used to derive sex-specific prognostic cut-off values. Of the cohort, 17,171 (58.5%) were men and 12,178 (41.5%) women, with mean follow-up 53.8 ± 23.0 months. The mean spKt/V was higher in women (1.71 ± 0.27) than in men (1.44 ± 0.22). In men, mortality was higher at spKt/V < 1.2 (HR 1.25, 95% CI 1.14–1.37), with no additional benefit at 1.4 or higher. In women, survival improved in the higher categories (1.4–1.7: HR 0.86; ≥ 1.7: HR 0.73). C-index analysis identified a prognostic cutoff of 1.21 for men and 1.51 for women. These findings suggest that uniform adequacy thresholds may not fully reflect sex-related prognostic differences. The identified spKt/V values should be interpreted as data-driven prognostic reference points rather than prescriptive treatment targets, and warrant validation in prospective studies.

Background: Health insurance plays a critical role in healthcare accessibility and outcomes, particularly for patients with end-stage kidney disease (ESKD). This retrospective observational study evaluated the relationships between health insurance status and rates of hospitalization and in-hospital mortality among patients with ESKD visiting the emergency department (ED).Methods: We retrospectively analyzed data from the National Emergency Department Information System in South Korea from January 2018 to December 2021. Patients were identified on the basis of their ICD-10 codes (N18.5) and categorized by health insurance type (Medical Aid [MA] recipients vs. National Health Insurance [NHI] beneficiaries). The primary outcomes were rates of hospitalization and in-hospital mortality from ED admission. Multivariate logistic regression models were used to assess the associations between insurance type and outcomes.Results: Among the 157,794 ED visits, 23.5% were by MA recipients and 76.5% by NHI beneficiaries. The participants in the MA group were younger than those in the NHI group, and the proportions of females and those with severe disease were lower in the MA group. After adjusting for age, sex, and the Korean Triage and Acuity Scale score, the MA group had a lower hospitalization risk but a risk of death similar to that of the NHI group. Patients <60 years of age had a lower hospitalization rate but a higher in-hospital mortality.Conclusion: Young, economically active MA patients were less likely to be admitted but had poor clinical outcomes after admission, suggesting their reluctance toward hospitalization for economic reasons.

Introduction: Patients with end-stage kidney disease (ESKD) are particularly vulnerable to adverse outcomes from coronavirus disease 2019 (COVID-19). We aimed to compare emergency department (ED) utilization patterns and clinical outcomes among patients with ESKD before and during the COVID-19 pandemic to inform future healthcare planning. Methods: We analyzed data from the National Emergency Department Information System (NEDIS), a nationwide database of ED visits in South Korea. Adult patients with ESKD who visited the ED between January 1, 2018, and May 31, 2021, were included. ED visits were categorized into pre- COVID-19 (2018-2019) and COVID-19 (2020-2021) periods based on visit date. Trends in ED visit frequency, presenting causes, clinical severity, hospitalization, and short-term mortality were compared using descriptive statistics and multi-variate logistic regression. Results: A total of 159,456 ED visits were analyzed (76,277 in 2018-2019; 83,179 in 2020-2021). Compared with the pre-pandemic period, ED visits during the COVID-19 period increased and were associated with higher odds of hospitalization [adjusted odds ratio (aOR), 1.054; 95% confidence interval (CI), 1.031–1.079] and mortality (aOR, 1.052; 95% CI, 1.007–1.099). This trend was most notable among patients presenting with severe conditions. Vascular access complications were the leading cause of ED visits during the COVID-19 period. Patients with severe illness were more likely to visit high-level hospitals and had higher rates of hospitalization and in-hospital mortality during the pandemic. Conclusion: The study found that patients with ESKD experienced an increase in ED visits during the COVID-19 pandemic, along with a higher risk of hospitalization and mortality; however, the distribution of patients across hospital service levels improved during the outbreak. These findings can inform preparedness strategies for future public health emergencies.

Background: Since hemodialysis (HD) patients are prone to various complications and high mortality, they need to be treated in HD units with professional personnel, proper equipment, and facilities. The Korean Society of Nephrology has been conducting an HD unit accreditation program since 2016. This study was performed to evaluate whether a qualified dialysis center (QDC) reduced the mortality of HD patients.Methods: This longitudinal, observational cohort study included 31,227 HD from 832 facilities. HD units were classified into two groups: the hospitals that have been certified as QDC between 2016 and 2018 (n = 219) and hospitals that have never been certified as QDC (non-QDC, n = 613). Baseline characteristics and patient mortality were compared between QDC vs. non-QDC groups using Korean HD quality assessment data from 2018. Multivariate logistic regression and the Cox proportional hazards model were used to compare patient mortality between the two groups.Results: Among study subjects, 30.6% of patients were treated at QDC and 69.4% were treated at non-QDC. The patients in the QDC were younger and had a longer dialysis duration, lower serum phosphorus and calcium levels, and higher hemoglobin and single-pool Kt/V levels compared to the patients from the non-QDC group. After adjusting for demographic and clinical parameters, QCD independently reduced mortality risk (hazard ratio, 0.897; 95% confidence interval, 0.847–0.950; p < 0.001).Conclusion: The HD unit accreditation program may reduce the risk of death among patients undergoing HD.

Background: Patients with end-stage kidney disease (ESKD) are more susceptible to viral epidemics and are known to have higher incidence and death rates of coronavirus disease 2019 (COVID-19) compared to the general population. We determined COVID-19 incidence and mortality among chronic hemodialysis (HD), peritoneal dialysis (PD), and kidney transplantation (KT) patients in Korea. Methods: We conducted a retrospective cohort study and data regarding Korean ESKD adults (aged ≥18 years) were obtained from the National Health Insurance Service of Korea from October 2020 to December 2021. We examined and compared the incidence of COVID-19–related infections and deaths among the patients receiving HD, PD, and KT. Results: Of all ESKD patients, 85,018 (68.1%) were on HD, 8,399 (6.7%) on PD, and 31,343 (25.1%) on KT. The COVID-19 incidence was 1.3% for HD, 1.2% for PD, and 1.5% for KT. COVID-19 mortality was 16.3% for HD, 12.2% for PD, and 4.7% for KT. PD patients had a lower incidence of infection compared to HD patients (odds ratio [OR], 0.76; 95% confidence interval [CI], 0.607–0.93), but KT patients had a significantly higher risk of infection (OR, 1.28; 95% CI, 1.13–1.44). Compared with HD, the risk of COVID-19–related death was not different for PD patients but was significantly lower for KT patients (hazard ratio, 0.55; 95% CI, 0.35–0.88). Conclusion: COVID-19 incidence was lower in PD patients than in HD patients, but mortality was not different between them. KT was associated with a higher risk of COVID-19 infection but lower mortality compared to HD.

Background: Assessing recent changes in mortality among patients undergoing hemodialysis (HD) can help both to identify the causes of death most closely associated with these changes and to develop prevention strategies. This study explored trends in all-cause and cause-specific mortality among patients undergoing HD in South Korea using an analysis of national data. Methods: We used national death certificate and claims data from 2003 to 2021 provided by the National Health Insurance Service. Age-standardized mortality rates (ASRs) were calculated by standardizing to the 2011 population of patients undergoing HD. Joinpoint regression analysis was performed to calculate the annual percentage change (APC) in mortality. All-cause and cause-specific ASRs and APCs were evaluated for the study period. Results: The proportion of male and older adult patients increased over time. In particular, the proportion of patients aged ≥ 80 years in the 2018–2021 period was more than 4 times higher than in the 2003–2007 period. From 2003 to 2021, there were a total of 136,302 deaths among patients undergoing HD in South Korea. Cardiovascular causes accounted for 13.6% of deaths, and the majority (86.4%) were attributed to noncardiovascular causes. In 2003, the all-cause ASR was 174.1 per 1000 person-years, which steadily decreased to 114.5 per 1000 person-years in 2021. The ASR from cardiovascular disease remained unchanged from 2003 to 2013 but increased by 3.9% (95% confidence interval: 1.3 to 14.0) per year from 2013 to 2021. In contrast, the ASR from noncardiovascular disease decreased during the study period. Conclusions: Nationally representative data showed a declining trend in the ASR among patients undergoing HD from 2003 to 2021. Noncardiovascular disease mortality decreased during the study period, while cardiovascular disease mortality increased.

Background: Intradialytic cardiac arrest is a serious complication of hemodialysis (HD) in patients with end-stage kidney disease. Therefore, appropriate emergency equipment should be prepared before the initiation of HD. However, little is known about the effects of preparedness of emergency equipment on the outcomes of patients undergoing HD. We aimed to evaluate the effects of preparedness of emergency equipment on mortality in Korean patients undergoing maintenance HD. Methods: Data from HD quality assessment and National Health Service claims between October and December 2015 were used. In total, 34,950 patients were categorized into two groups based on the availability of emergency equipment in the HD facilities. Cox proportional hazards models were used to assess the impact of preparedness of emergency equipment on patient mortality over a mean follow-up period of 53.7 ± 23.0 months. Results: The proportions of patients in the groups with and without emergency equipment were 95.2% (n = 33,267) and 4.8% (n = 1,683), respectively. Serum calcium and phosphorus levels, as well as systolic and diastolic blood pressures, were lower, whereas single-pool Kt/V was higher, in the group with emergency equipment than in the group without. After adjustment for demographic and clinical parameters, preparedness of emergency equipment was observed to be an independent risk factor for patient mortality (hazard ratio, 0.87; 95% confidence interval, 0.79-0.96; p = 0.004). Conclusion: Preparedness of emergency equipment was associated with decreased mortality among patients undergoing HD. A wellequipped HD unit can help increase patient survival.