The Epidemiology of Hepatitis B Virus Infection in Korea: 15-Year Analysis.

BACKGROUND: The purpose of this study is to investigate the epidemiological changes in chronic hepatitis B (CHB) and assess the impact of coronavirus disease 2019 (COVID-19) over the past 15 years in a region endemic to hepatitis B virus (HBV). METHODS: National Health Insurance Service claims data of hepatitis B patients spanning from 2007 to 2021 was utilized. To compare the characteristics of the hepatitis B group, a control group adjusted for age and gender through propensity score matching analysis was established. RESULTS: The number of patients with CHB has consistently increased over the past 15 years. The average age of the CHB patient group has shown a yearly rise, while the prevalence of male dominance has gradually diminished. The proportions of hepatocellular carcinoma, liver cirrhosis, and decompensation have exhibited a declining pattern, whereas the proportion of liver transplants has continuously risen. Patients with CHB have demonstrated significantly higher medical and medication costs compared to the control group. Moreover, patients with CHB have shown a higher prevalence of comorbidities along with a significantly higher rate of concomitant medication usage. During the COVID period, the HBV group experienced a substantial decrease in the number of outpatient visits and overall medical costs compared to the control group. CONCLUSION: The epidemiology of CHB has undergone significant changes over the past 15 years, encompassing shifts in prevalence, severity, medical costs, and comorbidities. Furthermore, the impact of COVID-19 has been observed to decrease healthcare utilization among patients with CHB when compared to controls.

Cerclage is associated with the increased risk of preterm birth in women who had cervical conization.

BACKGROUND: The aim of this study was to determine the effect of cerclage in women who underwent cervical conization. METHODS: Study data were collected from the Korea National Health Insurance Claims Database of the Health Insurance Review and Assessment Service for 2009-2013. Women who had a conization in 2009 and a subsequent first delivery between 2009 and 2013 in Korea were enrolled. RESULTS: Among the women who had conization in 2009, 1075 women had their first delivery between 2009 and 2013. A cerclage was placed in 161 of the women who were treated by conization. The rate of preterm birth was higher in the women who were treated with cerclage following a conization compared with those without cerclage (10.56 vs 4.27, p < 0.01, respectively). The multivariate regression analysis revealed that the women who were treated cerclage following a conization had an increased risk of preterm delivery compared with women without cerclage (odds ratio (OR), 2.6, 95% confidence interval (CI), 1.4-4.9). CONCLUSION: Our study showed that cerclage associated with an increased risk of preterm birth and preterm premature rupture of membranes in women who underwent conization. Further studies are required to clarify the mechanism by which cerclage affects the risk of preterm birth.

Preeclampsia Increases the Incidence of Postpartum Cerebrovascular Disease in Korean Population.

BACKGROUND: Multiple studies have been reported regarding preeclampsia as a possible risk factor of cerebrovascular disease (CVD). However, the correlation of preeclampsia and CVD, whether it is a cause-effect relationship or they are sharing common predisposing condition, is not well understood. Therefore, the aim of this study was to investigate the association between the preeclampsia during pregnancy and development of postpartum CVD. METHODS: A total of 1,384,550 Korean women who had a delivery between January 1, 2010 and December 31, 2012, were enrolled. Women with the risk of CVD within 1 year prior to pregnancy were excluded based on the Charlson comorbidity index. Primary endpoint was the event of CVD within a year from delivery. After exclusion, 1,075,061 women were analyzed. RESULTS: During the follow-up of 1 year postpartum, there were 25,577 preeclampsia out of 1,072,041 women without postpartum CVD (2.39%), and 121 of 3,020 women with postpartum CVD had preeclampsia before delivery (4.01%). In multivariate logistic regression analysis, women who had preeclampsia during pregnancy showed a higher risk for postpartum CVD (odds ratio, 1.64; 95% confidence interval, 1.37-1.98). CONCLUSION: The incidence of CVD after delivery was higher in women who had preeclampsia during pregnancy.

Towards Actualizing the Value Potential of Korea Health Insurance Review and Assessment (HIRA) Data as a Resource for Health Research: Strengths, Limitations, Applications, and Strategies for Optimal Use of HIRA Data.

Health Insurance and Review Assessment (HIRA) in South Korea, also called National Health Insurance (NHI) data, is a repository of claims data collected in the process of reimbursing healthcare providers. Under the universal coverage system, having fee-for-services covering all citizens in South Korea, HIRA contains comprehensive and rich information pertaining to healthcare services such as treatments, pharmaceuticals, procedures, and diagnoses for almost 50 million beneficiaries. This corpus of HIRA data, which constitutes a large repository of data in the healthcare sector, has enormous potential to create value in several ways: enhancing the efficiency of the healthcare delivery system without compromising quality of care; adding supporting evidence for a given intervention; and providing the information needed to prevent (or monitor) adverse events. In order to actualize this potential, HIRA data need to actively be utilized for research. Thus understanding this data would greatly enhance this potential. We introduce HIRA data as an important source for health research and provide guidelines for researchers who are currently utilizing HIRA, or interested in doing so, to answer their research questions. We present the characteristics and structure of HIRA data. We discuss strengths and limitations that should be considered in conducting research with HIRA data and suggest strategies for optimal utilization of HIRA data by reviewing published research using HIRA data.

The Incidence of Unexpected Uterine Malignancy in Women Undergoing Hysterectomy for a Benign Condition: A National Population-Based Study.

BACKGROUND: Potential risks associated with using a laparoscopic power morcellator have been reported in terms of the intraperitoneal seeding of benign and malignant diseases; therefore, knowing the precise incidence of unexpected uterine malignancy (UUM) would have clinically significant value. OBJECTIVE: The aim of this study was to investigate the incidence of UUM after a hysterectomy for benign conditions. METHODS: We analyzed the national inpatient sample data that were extracted by a stratified random sampling (sex and age) method from the Korean National Health Insurance Database between 1 January 2010 and 31 December 2012. RESULTS: Among 1,878,507 women treated during the study period, 12,850 women who underwent a hysterectomy for benign conditions were enrolled in this study. The mean age of these women was 47.22 ± 7.07 years. A laparotomic or laparoscopic hysterectomy was performed in 6623 and 6227 women, respectively, and UUM after hysterectomy was diagnosed in 24 women. No significant difference in the incidence of UUM was noted between the laparotomic and laparoscopic cases [laparotomy, 15 (0.23 %); laparoscopy, 9 (0.14 %); p = 0.28]. The incidence of UUM after hysterectomy was 0.19 % [confidence interval (CI) 0.11-0.26 %]; the incidence of unsuspected endometrial cancer after hysterectomy was 0.12 % (CI 0.06-0.19 %); and the incidence of UUM other than endometrial cancer after hysterectomy was 0.06 % (CI 0.02-0.11 %). CONCLUSION: This study shows that the incidence of UUM diagnosed after a hysterectomy for benign conditions was low, but has clinical significance with regard to the potential dissemination of UUM.

Comparison of Survival Outcomes in Women with Unsuspected Uterine Malignancy Diagnosed After Laparotomic Versus Laparoscopic Myomectomy: A National, Population-Based Study.

PURPOSE: The primary objective of our study was to investigate the effect of morcellation on overall survival in women with unsuspected uterine malignancy (UUM) diagnosed after myomectomy by comparing women who underwent laparotomic myomectomy to those who underwent laparoscopic myomectomy. The secondary objective was to estimate the incidence of UUM diagnosed after myomectomy. METHODS: We analyzed the mortality and incidence of women with UUM diagnosed after myomectomy using data from the national health insurance database between 2009 and 2013. To extract women with or without UUM diagnosed after myomectomy, we used diagnosis (C54.X) and procedure codes. We used the indicator of suspicion of death to verify deaths. RESULTS: During the study period, among the study population of approximately 23 million women per year, 102144 women underwent myomectomy. Of them, 69955 and 32085 women were enrolled onto the laparotomic and laparoscopic groups, respectively. In each group, the numbers of women with UUM diagnosed after myomectomy were 76 and 50, respectively. The incidences of UUM and UUM excluding endometrial cancer, respectively, were 0.1, 0.15 % (p = 0.046) and 0.05, 0.07 % (p = 0.147) in each group, respectively. The overall 3-year survival rates for patients with UUM and UUM excluding endometrial cancer were 97.6 ± 0.2 % (n = 23), 91.5 ± 0.5 % (n = 12); and 93.8 ± 0.6 % (n = 8), 93.8 ± 0.6 % (n = 5) in each group, respectively. Additionally, there were no statistically significant differences between the groups with respect to overall survival of women with UUM with or without endometrial cancer (log-rank test; p = 0.14) (time-dependent Cox regression model; p = 0.93). CONCLUSIONS: There was no difference in the overall survival of women with UUM with or without endometrial cancer between groups. The incidence of UUM with or without endometrial cancer diagnosed after myomectomy was quite low.

Prior cesarean section is associated with increased preeclampsia risk in a subsequent pregnancy.

BACKGROUND: To evaluate the impact of a prior cesarean section on preeclampsia risk in a subsequent pregnancy. METHODS: Study data were collected from the Korea National Health Insurance Claims Database of the Health Insurance Review and Assessment Service for 2006-2010. Patients who had their first delivery in 2006 and subsequent delivery between 2007 and 2010 in Korea were enrolled. The overall incidence of preeclampsia during the second pregnancy was estimated and to evaluate the risk of preeclampsia in the second pregnancy, a model of multivariate logistic regression analysis was performed with preeclampsia as the final outcome RESULTS: The risk of preeclampsia in any pregnancy was 2.17%; the risk in the first pregnancy was 2.76%, and that in the second pregnancy was 1.15%. During the second pregnancy, the risk of preeclampsia was 13.30% for women who had developed preeclampsia in their first pregnancy and 0.85% for those who had not. In the entire population, prior cesarean section was associated with preeclampsia risk in their subsequent pregnancy (odds ratio [OR], 1.26; 95% confidence interval [CI], 1.13-1.41). Among women with and without preeclampsia in their first pregnancy, a prior cesarean section was associated with preeclampsia risk in their second pregnancy (OR, 1.35; 95% CI, 1.09-1.67; OR, 1.23; 95% CI, 1.08-1.40, respectively). CONCLUSIONS: Our study showed that cesarean section in a first pregnancy was associated with increased preeclampsia risk in the second pregnancy. These results provide physicians with a preeclampsia risk evaluation method for a second pregnancy that they may aid counseling in patients.

Predicting Functional Outcome Based on Linked Data After Acute Ischemic Stroke: S-SMART Score.

Prediction of outcome after stroke may help clinicians provide effective management and plan long-term care. We aimed to develop and validate a score for predicting good functional outcome available for hospitals after ischemic stroke using linked data. A total of 22,005 patients with acute ischemic stroke from the Clinical Research Center for Stroke Registry between July 2007 and December 2014 were included in the derivation group. We assessed functional outcomes using a modified Rankin scale (mRS) score at 3 months after ischemic stroke. We identified predictors related to good 3-month outcome (mRS score ≤ 2) and developed a score. External validations (geographic and temporal validations) of the developed model were performed. The prediction model performance was assessed using the area under the receiver operating characteristic curve (AUC) and the calibration test. Stroke severity, sex, stroke mechanism, age, pre-stroke mRS, and thrombolysis/thrombectomy treatment were identified as predictors for 3-month good functional outcomes in the S-SMART score (total 34 points). Patients with higher S-SMART scores had an increased likelihood of a good outcome. The AUC of the prediction score was 0.805 (0.798-0.811) in the derivation group and 0.812 (0.795-0.830) in the geographic validation group for good functional outcome. The AUC of the model was 0.812 (0.771-0.854) for the temporal validation group. Moreover, they had good calibration. The S-SMART score is a valid and useful tool to predict good functional outcome following ischemic stroke. This prediction model may assist in the estimation of outcomes to determine care plans after stroke.

Incidence, Risk Factors, and Clinical Characteristics of Peripartum Cardiomyopathy in South Korea.

BACKGROUND: Peripartum cardiomyopathy (PPCM) is a rare disorder associated with pregnancy that can lead to life-threatening conditions. The incidence and clinical characteristics of this condition remain poorly understood. METHODS AND RESULTS: We aimed to perform the first population-based study of PPCM in South Korea, using the Korea National Health Insurance Claims Database of the Health Insurance Review and Assessment Service. Patients who fulfilled predefined diagnostic criteria for PPCM from January 1, 2010, to December 31, 2012, were identified from International Classification of Diseases, Tenth Revision, Clinical Modification codes. To discriminate PPCM from other causes of heart failure, we excluded subjects who already had heart failure-related International Classification of Diseases, Tenth Revision, Clinical Modification codes at least 1 year before delivery. During the study period, there were 1 404 551 deliveries in South Korea, and we excluded 20 159 patients who already had heart failure. In those, a total of 795 cases were identified as PPCM. Patients with PPCM were older, had a higher prevalence of preeclampsia and gestational diabetes mellitus, and were more likely to be primiparous and have multiple pregnancies. Moreover, cesarean section and pregnancy-related complications and in-hospital death were also more common in patients with PPCM. Intriguingly, a considerable number of heart failure cases (n=64; 8.1% of total PPCM) were noted between 5 and 12 months after delivery. CONCLUSIONS: The incidence of PPCM was 1 in 1741 deliveries in South Korea. Patients with PPCM were older, were more associated with primiparity and multiple pregnancy, had more pregnancy-related complications, and revealed higher in-hospital mortality than controls. The number of cases diagnosed as PPCM were decreased over time after delivery; however, a large number of patients were still noted through 12 months after delivery.

Obstetric risk factors for depression during the postpartum period in South Korea: a nationwide study.

OBJECTIVE: Postpartum depression is related to many adverse effects in both mothers and their children; therefore, proper screening and early interventions are needed. This study aims to identify the risk factors of postpartum depression. Our primary focus is on obstetric risk factors. METHODS: This study is a cross-sectional study which we extracted the data of women who gave birth between January 1st, 2010 and December 31st, 2012 from the Health Insurance Review and Assessment service (HIRA) database. We analyzed the data using multivariable logistic regression models. RESULTS: A total of 17,483 (1.4%) women suffered from depression during the postpartum period. Younger (<20years) and advanced maternal age (≥35years), primiparity, previous depression, peripartum hysterectomy, uterine artery embolization, preterm delivery, placental abruption, cesarean delivery, induced labor, and preeclampsia were found to increase the likelihood of having depression after delivery. CONCLUSIONS: Our findings suggest that there are several risk factors that lead women to postpartum depression. Therefore, early detection and well-management of the symptoms and risk factors for postpartum depression along with social support can help both physical and psychological conditions of women after childbirth.

Previous uterine artery embolization increases the rate of repeat embolization in a subsequent pregnancy.

This study aimed to determine the rate of repeat uterine artery embolization (UAE) in women with a previous UAE. Study data were collected from the Korea National Health Insurance Claims Database of the Health Insurance Review and Assessment Service for 2009-2013. We enrolled women who had a first delivery in 2009 and a second delivery between 2010 and 2013. Among 226,408 women who had a first delivery in 2009, 296 underwent UAE. A total of 127,506 women had a second delivery between 2010 and 2013. Of 296 women who underwent UAE after the first delivery, 94 had a second delivery between 2010 and 2013. Women with a previous UAE had a higher rate of UAE at the second delivery than women without a previous UAE. Multivariate adjusted analysis showed that a UAE at the first delivery increased the rate of UAE at the second delivery (odds ratio 25.56, 95% confidence interval 9.86-66.23). Women with a previous UAE should be appropriately counseled and monitored for the need for a repeat UAE.

Pregnancy-Associated Risk Factors of Postpartum Breast Cancer in Korea: A Nationwide Health Insurance Database Study.

Patients with postpartum breast cancer have been reported to have a poor prognosis. The present study aimed to evaluate the pregnancy-related risk factors of postpartum breast cancer in Korea. We collected patient data from the Korea National Health Insurance (KNHI) Claims Database of the Health Insurance Review and Assessment Service (HIRA) for the 2009-2013 period. We evaluated the pregnancy-related risk factors for postpartum breast cancer in two population groups. For Group 1 (women who had given birth during the 2010-2012 period), data on those who were diagnosed with breast cancer from childbirth to 1-year postpartum were extracted. For Group 2, we extracted the data of women who gave birth in 2010 and traced them until December 31, 2013. In Group 1, 1,384,551 deliveries and 317 postpartum breast cancer patients were recorded in Korea between January 1, 2010, and December 31, 2012. Women aged ≥35 years (Odds Ratio [OR], 2.003; 95% Confidence Interval [CI], 1.567-2.560) and those who gave birth via cesarean delivery (OR, 1.237; 95% CI, 0.986-1.553) were considered to be at a higher risk for breast cancer. Lower risk was noted in primiparous women (OR, 0.737; 95% CI, 0.585-0.928). In Group 2, the data of 457,924 women who gave birth in 2010 were traced until December 31, 2013. Among them, 655 patients were diagnosed with breast cancer, and age ≥35 years and cesarean delivery were associated with an higher risk of breast cancer, whereas primiparous status was associated with a lower risk of breast cancer. In conclusion, older age (≥35 years) and cesarean delivery are significant risk factors for postpartum breast cancer, and primiparous women have a lower risk of developing postpartum breast cancer.

Secular Trends of Gestational Diabetes Mellitus and Changes in Its Risk Factors.

OBJECTIVE: The aim of this study was to evaluate the secular trends of incidence of gestational diabetes mellitus (GDM) and insulin treatment for GDM in a Korean population and to determine the factors that contribute to the trends in the incidence of GDM. STUDY DESIGN: We used data collected by the Health Insurance Review & Assessment Service of Korea and analyzed data from women who had given birth from 2006 to 2010. We evaluated the trends in the incidence of GDM and GDM requiring insulin treatment and the changes in risk factors. RESULTS: There were 1,824,913 births during the study period, which included 129,666 cases of GDM, an incidence of 7.11% over this period. The incidence of GDM increased from 3.86% in 2007 to 11.83% in 2010, with a continuous increase after adjustment for age. However, the number of GDM cases that required insulin treatment decreased significantly from 13.87% in 2007 to 5.94% in 2010. The proportion of patients who were at an older age and multiparity, 2 GDM risk factors, increased during the study period. CONCLUSIONS: In Korea, the incidence of GDM, especially mild GDM, increased dramatically during the period from 2006 to 2010. Further efforts are needed to monitor this trend and to identify associated factors.

The epidemiology of reno-ureteral stone disease in Koreans: a nationwide population-based study.

The objective of this study was to evaluate the annual incidence of upper tract urolithiasis based on a large population-based study in Korea. This study used a subset of the 2009 Health Insurance and Review and Assessment service-National Patient Sample (HIRA-NPS). The 2009 HIRA-NPS contains data for 1,115,721 patients (711,285 inpatients and 404,436 outpatients) from January 2009 to December 2009. Based on these data, we selected patients who had been diagnosed with urolithiasis using the ICD code and calculated the incidence of urolithiasis. The total number of estimated urolithiasis patients was 219,328. The annual incidence of upper tract urolithiasis was estimated to be 457.02 per 100,000 in the overall population, with 589.09 per 100,000 men and 326.64 per 100,000 women. The male-to-female ratio was about 1.8:1. The annual incidence of urolithiasis in Korea was 457 per 100,000. It is higher than that previously reported in Japan, but lower than that in Western countries.

Trends in the rates of peripartum hysterectomy and uterine artery embolization.

The objective of this study was to determine the trends in national rates of peripartum hysterectomy (PH) and uterine arterial embolization (UAE) in Korea. We used data collected by the Health Insurance Review & Assessment Service of Korea and analyzed data from patients who gave birth during the period from 2005 to 2008. There were 1785,178 deliveries during the study period, including 2636 cases of PH (1.48 per 1000 deliveries). The PH rate in 2005 was 1.57 per 1000 deliveries and in 2008 it was 1.33 per 1000 deliveries. UAE was performed in 161 women (incidence, 0.38 per 1000 deliveries) and 447 women (incidence, 0.98 per 1000 deliveries) in 2005 and 2008, respectively. In Korea, the rate of PH decreased slightly, while the rate of UAE rate increased dramatically during the period from 2005 to 2008. Further studies are needed to evaluate the effects of UAE on the rate of PH performed.