Autoimmune disorders reported following COVID-19 vaccination: A disproportionality analysis using the WHO database.

PURPOSE: Owing to adverse event following immunization (AEFI) related to autoimmune disorders and coronavirus disease 2019 (COVID-19) vaccines sharing common biological mechanisms, identifying the risk of AEFIs associated with COVID-19 vaccines remains a critical unmet need. We aimed to assess the potential safety signals for 16 AEFIs and explore co-reported adverse events (AEs) and drugs using the global database of the World Health Organization, VigiBase. METHODS: We assessed the occurrence of 16 AEFIs following COVID-19 vaccination through the Standardized MedDRA Queries group "Immune-mediated/Autoimmune Disorders" from MedDRA and performed a disproportionality analysis using reporting odds ratio (ROR) and information component (IC) with 95% confidence intervals (CIs). RESULTS: We identified 25,219 events associated with COVID-19 vaccines in VigiBase. Although rare, we detected four potential safety signals related to autoimmune disorders following COVID-19 vaccination, including ankylosing spondylitis or psoriatic arthritis (ROR 1.86; 95% CI 1.53-2.27), inflammatory bowel disease (ROR 1.77; 95% CI 1.60-1.96), polymyalgia rheumatica (ROR 1.42; 95% CI 1.30-1.55), and thyroiditis (ROR 1.40; 95% CI 1.30-1.50), with positive IC025 values. The top co-reported AEs were musculoskeletal disorders, and immunosuppressants were the most representative co-reported drugs. CONCLUSION: In addressing the imperative to comprehend AEFI related to autoimmune disorders following COVID-19 vaccination, our study identified four potential safety signals. Thus, our research underscores the importance of proactive safety monitoring for the identification of the four AEFIs following COVID-19 vaccination, considering the associated advantages.

Effectiveness and Safety of COVID-19 Vaccination During Preconceptional and Preclinical Pregnancy Period: A National Population Study.

BACKGROUND: We aimed to assess the risk of maternal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and early abortive outcomes after the association between coronavirus disease 2019 (COVID-19) vaccination during the preconceptional period and preclinical pregnancy, which are likely to be inadvertent vaccination. METHODS: We used data from the Korea Disease Control and Prevention Agency-COVID19-National Health Insurance Service cohort from December 2020 to December 2021. The vaccinated pregnant women were matched to unvaccinated pregnant controls at a 1:4 ratio. The risks of SARS-CoV-2 infection and intensive care unit (ICU) admission within 14 days of infection were analyzed to assess its effectiveness. For safety measures, the adjusted relative risks (aRRs) of early abortive outcomes for the first COVID-19 vaccination during the preconceptional and preclinical periods were calculated considering covariates. We compared the risk of early abortion between mRNA and viral vector vaccines. RESULTS: The overall COVID-19 vaccination rates during the preconceptional period and preclinical pregnancy were 3.1% (6,662/215,211) and 2.6% (5,702/215,211), respectively. The cumulative incidence of ICU admission within 14 days of SARS-CoV-2 infection was 6/100,000 in the unvaccinated group, whereas there were no ICU admissions in the vaccinated groups. The risks of early abortive outcomes were not significantly different between the preconceptional vaccination group and the unvaccinated group (aRR, 1.04; 95% confidence interval [CI],0.99-1.10) or between preclinical pregnancy vaccination and their matched controls (1.02; 95% CI, 0.96-1.08). mRNA and viral vector vaccines have shown similar risks for early abortive outcomes and miscarriages. CONCLUSION: Our findings have provided compelling evidence regarding the effectiveness and safety of COVID-19 vaccination prior to and during early pregnancy. Further research is required to extend the safety and efficacy profiles of COVID-19 vaccines to pregnant women and their babies.

Treatment patterns and cost of exacerbations in patients with chronic obstructive pulmonary disease using multiple inhaler triple therapy in South Korea.

BACKGROUND: Multiple inhaler triple therapy (MITT), comprising inhaled corticosteroids (ICS), long-acting beta-agonists (LABA), and long-acting muscarinic antagonists (LAMA), has been used as an escalation treatment for patients with chronic obstructive pulmonary disease (COPD). However, real-world use of MITT has not been investigated in Asia, including South Korea. This study reports baseline characteristics of patients with COPD initiated on MITT in South Korea, and their treatment patterns. Healthcare resource utilization (HRU) and costs associated with COPD exacerbations following MITT initiation were also assessed. METHODS: This was a retrospective cohort study using the South Korea National Health Insurance database (2014-2018). Included patients were ≥ 40 years, had a COPD diagnosis, were newly initiated on MITT and had ≥ 12 months' data both before (baseline) and after index date (the first day with overlapping supply of all MITT components). Treatment immediately before initiation and immediately following discontinuation of MITT were identified, and proportion of days covered (PDC) by MITT was calculated. HRU and costs (per person per year [PPPY]) associated with exacerbations were identified following MITT initiation; costs were calculated using the average 2020 exchange rate (0.0008 USD/KRW). RESULTS: Among 37,400 patients, the mean age was 69 (SD 10) years and 73% were males; 56% had ≥ 1 COPD exacerbation during the baseline period, with a mean of 2 (SD 5) events/year. ICS/LABA was the most frequent regimen prescribed immediately before initiation (37%) and immediately following discontinuation (41% of 34,264 patients) of MITT. At 3, 6, and 12 months from treatment initiation, mean PDC was 81%, 63% and 49%, respectively; median treatment duration was 102 days. The mean (95% confidence interval [CI]) number of total visits for severe COPD exacerbations was 0.77 PPPY (0.75-0.78); mean PPPY total healthcare costs were 2093 USD. CONCLUSIONS: Patients with COPD in South Korea experienced frequent exacerbations prior to MITT, and PDC by MITT was low. Patients may benefit from early optimization of COPD therapy, and greater emphasis on adherence to inhaled COPD therapy. Severe exacerbations were found to incur substantial costs; treatment alternatives that can reduce the rate of severe exacerbations are likely to minimize healthcare costs.

Suitability of databases in the Asia-Pacific for collaborative monitoring of vaccine safety.

INTRODUCTION: Information regarding availability of electronic healthcare databases in the Asia-Pacific region is critical for planning vaccine safety assessments particularly, as COVID-19 vaccines are introduced. This study aimed to identify data sources in the region, potentially suitable for vaccine safety surveillance. This manuscript is endorsed by the International Society for Pharmacoepidemiology (ISPE). METHODS: Nineteen countries targeted for database reporting were identified using published country lists and review articles. Surveillance capacity was assessed using two surveys: a 9-item introductory survey and a 51-item full survey. Survey questions related to database characteristics, covariate and health outcome variables, vaccine exposure characteristics, access and governance, and dataset linkage capability. Other questions collated research/regulatory applications of the data and local publications detailing database use for research. RESULTS: Eleven databases containing vaccine-specific information were identified across 8 countries. Databases were largely national in coverage (8/11, 73%), encompassed all ages (9/11, 82%) with population size from 1.4 to 52 million persons. Vaccine exposure information varied particularly for standardized vaccine codes (5/11, 46%), brand (7/11, 64%) and manufacturer (5/11, 46%). Outcome data were integrated with vaccine data in 6 (55%) databases and available via linkage in 5 (46%) databases. Data approval processes varied, impacting on timeliness of data access. CONCLUSIONS: Variation in vaccine data availability, complexities in data access including, governance and data release approval procedures, together with requirement for data linkage for outcome information, all contribute to the challenges in building a distributed network for vaccine safety assessment in the Asia-Pacific and globally. Common data models (CDMs) may help expedite vaccine safety research across the region.

Machine Learning Approach for Active Vaccine Safety Monitoring.

BACKGROUND: Vaccine safety surveillance is important because it is related to vaccine hesitancy, which affects vaccination rate. To increase confidence in vaccination, the active monitoring of vaccine adverse events is important. For effective active surveillance, we developed and verified a machine learning-based active surveillance system using national claim data. METHODS: We used two databases, one from the Korea Disease Control and Prevention Agency, which contains flu vaccination records for the elderly, and another from the National Health Insurance Service, which contains the claim data of vaccinated people. We developed a case-crossover design based machine learning model to predict the health outcome of interest events (anaphylaxis and agranulocytosis) using a random forest. Feature importance values were evaluated to determine candidate associations with each outcome. We investigated the relationship of the features to each event via a literature review, comparison with the Side Effect Resource, and using the Local Interpretable Model-agnostic Explanation method. RESULTS: The trained model predicted each health outcome of interest with a high accuracy (approximately 70%). We found literature supporting our results, and most of the important drug-related features were listed in the Side Effect Resource database as inducing the health outcome of interest. For anaphylaxis, flu vaccination ranked high in our feature importance analysis and had a positive association in Local Interpretable Model-Agnostic Explanation analysis. Although the feature importance of vaccination was lower for agranulocytosis, it also had a positive relationship in the Local Interpretable Model-Agnostic Explanation analysis. CONCLUSION: We developed a machine learning-based active surveillance system for detecting possible factors that can induce adverse events using health claim and vaccination databases. The results of the study demonstrated a potentially useful application of two linked national health record databases. Our model can contribute to the establishment of a system for conducting active surveillance on vaccination.

Impact of Malaria in Pregnancy on Risk of Malaria in Young Children: Systematic Review and Meta-Analyses.

BACKGROUND: Our objective was to quantify the risk of acquiring malaria among progeny of women with malaria during pregnancy. METHODS: We searched MEDLINE, EMBASE, CINAHL, and the Cochrane Library for eligible prospective studies. The primary predictor was malaria during pregnancy defined as placental malaria, parasitemia, clinical malaria, or pregnancy-associated malaria. Primary outcomes were parasitemia or clinically defined malaria of young children. We performed meta-analyses to pool adjusted risk estimates using a random-effects model. RESULTS: Nineteen of 2053 eligible studies met inclusion criteria for the systemic review. Eleven of these studies were quantitative and were included in the meta-analyses. The pooled adjusted odds ratio (aOR) or adjusted hazard ratio (aHR) of malaria during pregnancy for detection of parasitemia in young children were 1.94 (95% confidence interval [CI], 0.93-4.07; P = .08) and 1.46 (95% CI, 1.07-2.00; P < .001), respectively. The pooled aOR or aHR for clinically defined malaria in young children were 2.82 (95% CI, 1.82-4.38; P < .001) and 1.31 (95% CI, 0.96-1.79; P = .09), respectively. CONCLUSIONS: Our results confirmed that malaria during pregnancy significantly increased the overall risk of malaria in young children via indeterminate mechanisms and emphasize the urgent need to implement safe and highly effective strategies to prevent malaria during pregnancy.

A Systematic Review of the National Breast Implant Registry for Application in Korea: Can We Predict "Unpredictable" Complications?

Background and Objectives: Since silicone breast implants were introduced to the market several decades ago, the safety of breast implants has remained controversial. Recently, several studies have explored breast implant-associated anaplastic large-cell lymphoma (BIA-ALCL) and breast implant illness (BII). Several countries have developed national breast implant registries to improve the safety and quality of breast implant surgery. We performed a systematic review of the current status of national breast implant registries and propose a pilot form of an appropriate breast implant registry model for Korea. Materials and Methods: The systematic review was conducted in accordance with the "preferred reporting items for systematic reviews and meta-analyses (PRISMA) pro forma". PubMed and Google Scholar databases were searched to identify all articles containing information on national breast implant registries. We limited the search to articles written in the English language from 2010 to 2020. Articles were reviewed by two independent authors. Results: A total of 63 articles related to national breast implant registries, registry principles and national breast implant registry annual reports were identified. After reviewing the literature, 25 national breast implant registry-related articles were included in the full-text synthesis. Currently, four countries, The Netherlands, Australia, Sweden, and the UK, have breast implant registries with well-formed sources for big data. Overall, similarities in data points were detected for three categories: implant-related complications, operation details, and device information. However, there were differences for each registry in terms of governance, funding, and capture rate. Conclusion: After reviewing other countries' experiences, tentative datasets for the Korean Breast Implant Registry (K-BIR) were developed. The K-BIR can improve the quality of breast implant surgery in Korea by providing datasets on overall processes and outcome measures with quality indicators and risk adjustment factors. This approach will register characteristics of patients and monitor breast implants, complications, and surgical procedures to improve the outcomes of breast implant surgery in Korea. In addition, it can be used as a track-and-trace system with automated notifications to patients in the event of a product recall or other safety concerns related to a specific type of implant.

The association between antidepressant use and deaths from road traffic accidents: a case-crossover study.

PURPOSE: Antidepressants are some of the most commonly used psychiatric medications, but little information is available about the effects of antidepressant treatment on the risk of traffic accidents across classes of antidepressants or associated with each substance individually. To investigate the relationship between exposure to antidepressants and risk of fatality in road traffic accidents. METHODS: We used a Korean national road traffic authority database linked with a national health insurance database between January 1, 2010 and December 31, 2014 and applied a case-crossover design. The study subjects were drivers in South Korea who died from traffic accidents and who had prescriptions for antidepressants within 1 year prior to the date of the accident. We compared the status of prescription for antidepressants with the hazard period and four matched control periods using conditional logistic regression, adjusting for other drug use. The trends of antidepressant utilization were described in terms of the number of prescriptions. A case-case-time-control design was applied to drugs with an increasing trend in use and a significant case-crossover odds ratio (OR). RESULTS: A total of 1250 antidepressant-using drivers were included, and an increased risk was observed during the 30-day hazard period (adjusted OR 1.30; 95% CI 1.03-1.63). Selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) showed significant risks, but tricyclic antidepressants did not. However, the associations of all antidepressants, SSRIs, SNRIs, escitalopram, and duloxetine did not remain significant after adjusting for trends in utilization. Paroxetine and milnacipran were associated with increased risks, with no obvious increase in their utilization, but the possibility of confounding by indication could have affected the results for milnacipran. CONCLUSION: Considering the trends of antidepressant prescription and utilization, the use of paroxetine increased the risk of fatal traffic accidents.

The relationships between timing of first childbirth, parity, and health-related quality of life.

PURPOSE: A few studies have investigated the relationship between age at first childbirth and health-related quality of life (HRQoL). This study examined the relationship between age at first childbirth and HRQoL and whether parity mediates this timing of the first childbirth-HRQoL relationship in women aged 50 years or above. METHODS: The study population included 5146 parous women ≥ 50 years in the cross-sectional survey, the Korea National Health and Nutrition Examination Survey 2010-2012. HRQoL was evaluated by the EuroQol five-dimensional descriptive system. Participants were grouped according to quartiles of age at first childbirth (ranges: 13-21, 22-23, 24-25, and 26-44 years). This study used linear regression analysis to examine the relationship between age at first childbirth and HRQoL and on each dimension. Mediation analysis was used to examine the contribution of age at first childbirth to HRQoL and to each dimension. RESULTS: This study found the increasing pattern of HRQoL across quartiles of age at first childbirth (P for trend = 0.030). Odds of problems in self-care and anxiety/depression dimensions significantly increased across the quartiles. Women with later age at first childbirth tended to have better HRQoL (B = 0.352, P = 0.003); parity significantly contributed to this relationship. Decreasing parity accounted for 33.5% of the relationship between late first childbirth and increased HRQoL. Early age at first childbirth significantly increased odds of the mobility problem through increasing parity. CONCLUSIONS: Women of an early age at first childbirth tended to have lower HRQoL through giving more deliveries. Our findings suggest that more attention needs to be given to women with early pregnancy and more delivery to prevent impaired HRQoL.

AGE, SEX, AND TIME-SPECIFIC TRENDS IN SURGICAL APPROACHES FOR RHEGMATOGENOUS RETINAL DETACHMENT: A Nationwide, Population-Based Study Using the National Claim Registry.

PURPOSE: To investigate the primary surgical approach for rhegmatogenous retinal detachment (RRD) according to age group, sex, and year in Korea. METHODS: We retrospectively identified patients from the national claims database who underwent primary surgery for RRD from 2007 to 2011 using the diagnostic code and surgical codes for RRD. Patients were categorized into three groups according to surgical treatment; scleral buckling, vitrectomy, and combined operation. We analyzed the frequency and proportion of primary surgical approach for RRD according to age group, sex, and year. RESULTS: Of 24,928 RRD patients, 11,372 (45.6%) patients underwent scleral buckling, 10,583 (42.5%) patients underwent vitrectomy, and 2,973 (11.9%) underwent a combined operation. Regression analysis showed that relative proportion of surgical approach had linear relationship with age; the percentage of patients undergoing vitrectomy increased by an average of 7.55% every 10 years (P < 0.001). This age-related trend was observed for both sexes. Scleral buckling tended to be preferred in younger patients (<45 years) and vitrectomy in older patients (≥45 years). Men tended to undergo vitrectomy significantly more than women in patients aged 15 years to 34 years. There was no consistent trend over time in the primary surgical approach during the study period. CONCLUSION: Age and sex of RRD patients influence the selection of primary surgical approaches. Young patients tend to undergo scleral buckling, whereas older patients tend to receive vitrectomy. Among young patients, men are more likely to undergo vitrectomy than women. No discernible trend over time was observed in the surgical approach over the 5-year study period.

Prevalence and Incidence of Exudative Age-Related Macular Degeneration in South Korea: A Nationwide Population-Based Study.

PURPOSE: To determine the prevalence and incidence of exudative age-related macular degeneration (AMD) in South Korea. DESIGN: Nationwide population-based retrospective study using data from the Korean national health claims database from 2008 through 2012. PARTICIPANTS: Entire South Korean population 40 years of age or older (n = 22,376,510). METHODS: We accessed the national health claims database to identify exudative AMD patients using the registration program database for rare intractable diseases, which included ophthalmologist-confirmed exudative AMD, for copayment reduction. MAIN OUTCOME MEASURES: Prevalence and incidence rates of exudative AMD. RESULTS: During the 5-year study period, 81 513 patients had exudative AMD (48.2% men) and were included in the prevalence estimates. The prevalence in the general population 40 years of age or older was 36.43 (95% confidence interval [CI], 36.18-36.68) per 10,000 people, that in men was 37.01 (95% CI, 36.65-37.38) per 10,000 people, and that in women was 35.90 (95% CI, 35.56-36.24) per 10,000 people. After excluding prevalent cases during the initial 2-year washout period, 20,196 cases were identified with incident exudative AMD during the final 3-year study period (2010-2012). The incidence in the general population 40 years of age or older was 3.02 (95% CI, 2.98-3.06) per 10,000 person-years, that in men was 3.76 (95% CI, 3.69-3.83) per 10,000 person-years, and that in women was 2.34 (95% CI, 2.29-2.39) per 10,000 person-years. The prevalence and incidence increased with advancing age and peaked at approximately 80 years of age. Both the prevalence and incidence were higher in men than in women in all age groups. CONCLUSIONS: These detailed estimates of the nationwide, population-based prevalence and incidence of exudative AMD in an Asian population may help to understand the disease pathophysiology and to plan accordingly within the healthcare system.

Risk and Risk Periods for Stroke and Acute Myocardial Infarction in Patients with Central Retinal Artery Occlusion.

PURPOSE: To investigate the risk of stroke and acute myocardial infarction (AMI) in patients with incident central retinal artery occlusion (CRAO). DESIGN: A self-controlled case series (SCCS) study. PARTICIPANTS: Patients with incident CRAO from the entire Korean population of 48 million individuals. METHODS: We used the Korean national claim database (2007-2011) for analyses. After identifying patients with incident CRAO, the relative incidence rate ratios (IRRs) for stroke and AMI in risk periods were measured in these patients using a SCCS method. MAIN OUTCOME MEASURES: The IRRs of stroke and AMI by risk periods. RESULTS: Of 1655 patients with incident CRAO in 2009-2010, 165 had stroke/AMI (ischemic stroke in 139, hemorrhagic stroke in 13, and AMI in 15) in the observation period spanning 365 days before and after the occurrence of CRAO. The IRR of stroke/AMI 1 to 30 days after CRAO occurrence significantly increased (14.0; 95% confidence interval [CI], 8.90-22.00); the IRR peaked during the 1 to 7 days after CRAO occurrence (44.51; 95% CI, 27.07-73.20), and the increased risk was present for the first 30 days. The IRR of stroke/AMI also significantly increased 1 to 30 days (6.82; 95% CI, 4.01-11.60) and 31 to 90 days (2.86; 95% CI, 1.66-4.93) before CRAO occurrence. Subanalysis for only ischemic stroke showed similar, magnified IRRs in the risk periods compared with all events. The IRRs were not significantly different between sexes or age groups (<65 vs. ≥65 years). CONCLUSIONS: Patients with incident CRAO are at increased risk of ischemic stroke just after CRAO occurrence, and the risk is particularly increased during the first week immediately after the CRAO occurrence. The results suggest that patients with incident CRAO require immediate neurologic evaluation and preventive treatment to reduce mortality and morbidity.

The Impact of Green Tea Consumption on the Prevention of Hemorrhagic Stroke.

BACKGROUND: Different types of tea may have varying effects on the risk of hemorrhagic stroke, but previous studies have generated inconsistent results. We performed a nationwide, multi-center, case-control study to evaluate the association between the consumption of tea and the risk of hemorrhagic stroke. METHODS: This study included 940 patients aged 30 to 84 with non-traumatic acute hemorrhagic stroke who did not have a history of stroke or hemorrhage-prone brain lesions, as well as 940 community controls and 940 hospital controls matched to each patient by age and gender. Pre-trained interviewers obtained information on potential confounders. Consumption of tea was assessed by using a food frequency questionnaire. Participants were asked to indicate the number of cups of tea (green, black, and oolong tea) they consumed per day or per week during the preceding year. RESULTS: The adjusted odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated by conditional logistic regression. The adjusted ORs of hemorrhagic stroke were 0.71 (95% CI: 0.59-0.87), 0.86 (95% CI: 0.55-1.37), and 1.34 (95% CI: 0.91-1.98) for consumption of green, oolong, and black tea, respectively, compared with no consumption. There was no significant linear trend for green tea consumption. CONCLUSIONS: Consumption of green tea may protect against hemorrhagic stroke, whereas consumption of black tea may have no meaningful effect on risk.

Prescription sequence symmetry analysis: assessing risk, temporality, and consistency for adverse drug reactions across datasets in five countries.

BACKGROUND: Prescription sequence symmetry analysis (PSSA) is a signal detection method for adverse drug events. Its capacity to consistently detect adverse drug events across different settings has not been tested. We aimed to determine the consistency of PSSA results for detecting positive and negative control adverse drug events across different settings. METHODS: Using a distributed network model, we analyzed prescription dispensing data using PSSA in Australia, Hong Kong, Japan, Korea, and Taiwan. Positive control was amiodarone and thyroxine, as a marker of amiodarone-induced hypothyroidism, a known adverse event with a clear temporal relationship to amiodarone initiation. Negative controls were amiodarone and allopurinol, as a marker of amiodarone-induced gout and thyroxine and allopurinol, as a marker of thyroxine-induced gout. Gout is not recorded as an adverse event in product information for either medicine. Adjusted sequence ratios (ASR) were calculated for each country. Pooled estimates were obtained by using the generic inverse variance method. RESULTS: A positive association was identified between amiodarone and thyroxine in all settings with a pooled ASR 2.63 (95% confidence interval (CI) 1.47-4.72). Temporal analysis showed the effect occurred within the first few weeks of treatment. No significant associations were found for the negative controls in any setting; pooled ASR were 0.76 (95%CI 0.62-0.93) and 0.98 (95%CI 0.85-1.12) for amiodarone-allopurinol and thyroxine-allopurinol, respectively. CONCLUSION: Despite different health settings, different populations, and different patterns of medicine utilization, PSSA gave consistent estimates across countries for a well-known positive association and two negative control adverse events.

Nationwide incidence of clinically diagnosed retinal vein occlusion in Korea, 2008 through 2011: preponderance of women and the impact of aging.

OBJECTIVE: This study aimed at defining the incidence and demographics of clinically diagnosed retinal vein occlusion (RVO) in Korea. DESIGN: Nationwide population-based retrospective study using data entered into the Korean national health claims database from 2007 through 2011. PARTICIPANTS: Data of the entire population of Korea (n = 47,990,761, based on the 2010 census) were analyzed. METHODS: The Korean national health claims database was analyzed to identify patients with RVO. Incident cases included individuals with no RVO claims in 2007, but with RVO claims in the years 2008 through 2011. The incidence rate of RVO was estimated for the entire Korean population. MAIN OUTCOME MEASURES: The person-time incidence rates of clinically diagnosed RVO in Korea, including the age- and gender-specific incidence rates, were estimated. RESULTS: A total of 92 730 RVO cases (56.4% in women) were identified. The incidence rate of clinically diagnosed RVO during the study period was 48.31 per 100,000 person-years (95% confidence interval [CI], 48.00-48.62). The incidence rate among men and women was 42.40 (95% CI, 41.99-42.81) and 54.14 (95% CI, 53.67-54.60) per 100,000 person-years, respectively (P < 0.001). The highest incidence of 214.92 per 100,000 person-years (95% CI, 211.29-218.56) was observed in the age group of 70 to 74 years (186.62 [95% CI, 181.46-191.78] and 236.25 [95% CI, 231.21-241.29] per 100,000 person-years for men and women aged 70 to 74 years, respectively). The incidence rate of RVO increased as the age of the population increased-more than doubling approximately every 10 years from the second to the seventh decade of life. Retinal vein occlusion occurred more often in men 30 to 54 years of age and in men older than 85 years, but was more common in women 55 to 84 years of age. CONCLUSIONS: This study reports the population-based RVO incidence in Korea. The RVO incidence increased exponentially as the age of the population increased, and the RVO incidence in women was 1.28 times higher than that in men.

Nationwide incidence of clinically diagnosed central retinal artery occlusion in Korea, 2008 to 2011.

PURPOSE: To define the incidence and demographics of clinically diagnosed central retinal artery occlusion (CRAO) in Korea. DESIGN: Nationwide population-based retrospective study using data entered into the Korean national health claims database from 2007 to 2011. PARTICIPANTS: Data of the entire Korean population (N = 47,990,761, based on the 2010 census) were analyzed. METHODS: We used the national health claims database to identify patients diagnosed with CRAO. Incident cases were those with no claims related to CRAO in 2007 and were included once on the earliest claims related to CRAO in the years 2008 to 2011. Incident cases had a disease-free period before diagnosis of at least 1 to 4 years. The average incidence rate of CRAO was estimated according to the entire Korean population. MAIN OUTCOME MEASURES: The person-time incidence rates of clinically diagnosed CRAO in Korea, including the age- and sex-specific incidence rates, were estimated. RESULTS: A total of 3464 CRAO cases (59.1% men) were identified. The incidence rate of clinically diagnosed CRAO during the study period was 1.80 per 100,000 person-years (95% confidence interval [CI], 1.74-1.86). The incidence rate among men and women was 2.15 (95% CI, 2.05-2.24) and 1.47 (95% CI, 1.39-1.54) per 100,000 person-years (male-to-female ratio, 1.47), respectively. The age-specific male-to-female ratios were constant between the ages of 30 and 89 years (range, 1.51-2.10 years). The highest incidence of 10.08 (95% CI, 8.80-11.35) per 100,000 person-years was observed in those aged 80 to 84 years (14.65 [95% CI, 11.90-17.40] and 8.00 [95% CI, 6.63-9.37] per 100,000 person-years for men and women aged 80-84 years, respectively). The incidence rate of CRAO increased exponentially with age until the 9th decade of life. CONCLUSIONS: To our knowledge, this is the first nationwide epidemiologic study of CRAO in individuals of all ages. The incidence rate of CRAO in Korea increased exponentially with increasing age and was highest among those aged 80 to 84 years. Moreover, the incidence rate in men was 1.47 times higher than that in women.

Acute renal failure following oral sodium phosphate bowel preparation: a nationwide case-crossover study.

BACKGROUND AND STUDY AIMS: Oral sodium phosphate (OSP) is a cleansing agent for colonoscopy. Recent reports have cited an increased risk of acute renal failure (ARF) in OSP bowel purgative users, but this risk remains under debate. This study was performed to evaluate the association between OSP and ARF in patients who underwent colonoscopy. PATIENTS AND METHODS: A population-based case-crossover study was conducted using the Korean Health Insurance Review and Assessment Service (HIRA) claims data from 1 January 2005 to 31 December 2009. The study population consisted of patients aged ≥ 50 years who underwent colonoscopies after an OSP prescription prior to their first hospitalization for ARF. For each patient, one hazard and four control periods were matched at specified time windows. Conditional logistic regression analysis was used to estimate the odds ratio (OR) and 95 % confidence interval (CI), adjusting for concomitant medications that could induce ARF. RESULTS: A total of 1105 patients were included (54 % male). The adjusted ORs for ARF related to the use of OSP when applying the 1-, 2-, 4-, 8-, or 12-week time windows were 3.7 (95 %CI 2.37 - 5.67), 3.5 (95 %CI 2.45 - 4.89), 3.0 (95 %CI 2.30 - 3.95), 2.4 (95 %CI 1.93 - 2.96), and 2.0 (95 %CI 1.69 - 2.46), respectively. When adopting an 8-week time window, the adjusted OR was 2.5 (95 %CI 1.98 - 3.16) for the subgroup without chronic renal failure. CONCLUSIONS: The use of OSP was significantly associated with ARF both in patients with and without co-morbidities.

Utilization patterns of disease-modifying antirheumatic drugs in elderly rheumatoid arthritis patients.

This study was conducted to investigate disease-modifying antirheumatic drug (DMARD) utilization in Korean elderly patients with rheumatoid arthritis (RA). We used data from January 1, 2005 to June 30, 2006 from the Health Insurance Review and Assessment Service claims database. The study subjects were defined as patients aged 65 yr or older with at least two claims with a diagnosis of RA. DMARD use was compared by the patients' age-group, gender, medical service, and geographic divisions. The patterns of DMARD use in mono- and combination therapy were calculated. RA medication use was calculated by the number of defined daily doses (DDD)/1,000 patients/day. A total of 166,388 patients were identified during the study period. DMARD use in RA patients was 12.0%. The proportion of DMARD use was higher in the younger elderly, females, and patients treated in big cities. Hydroxychloroquine was the most commonly used DMARD in monotherapy, and most of the combination therapies prescribed it with methotrexate. DMARD use in elderly RA patients was noticeably low, although drug prescriptions showed an increasing trend during the study period, clinicians may need to pay more attention to elderly RA patients.

Prevention of venous thromboembolism, 2nd edition: Korean Society of Thrombosis and Hemostasis Evidence-based Clinical Practice Guidelines.

In 2010, we proposed the first Korean Guidelines for the Prevention of Venous Thromboembolism (VTE). It was applicable to Korean patients, by modifying the contents of the second edition of the Japanese guidelines for the prevention of VTE and the 8th edition of the American College of Chest Physicians (ACCP) evidence-based clinical practice guidelines. From 2007 to 2011, we conducted a nationwide study regarding the incidence of VTE after major surgery using the Health Insurance Review and Assessment Service (HIRA) database. In addition, we have considered the 9th edition of the ACCP Evidenced-Based Clinical Practice Guidelines, published in 2012. It emphasized the importance of clinically relevant events as opposed to asymptomatic outcomes with preferences for both thrombotic and bleeding outcomes. Thus, in the development of the new Korean guidelines, three major points were addressed: 1) the new guidelines stratify patients into 4 risk groups (very low, low, moderate, and high) according to the actual incidence of symptomatic VTE from the HIRA databases; 2) the recommended optimal VTE prophylaxis for each group was modified according to condition-specific thrombotic and bleeding risks; 3) guidelines are intended for general information only, are not medical advice, and do not replace professional medical care and/or physician advice.

Changes in vaccination practices among infants after the introduction of DTaP-IPV/Hib combination vaccines.

Background: Diphtheria-tetanus-acellular pertussis, polio, and Haemophilus influenza type B (DTaP-IPV/Hib) combination vaccine was introduced as a part of the Korea National Immunization Program (NIP) on June 19, 2017. Combination vaccines can improve vaccination rates by simplifying the vaccination schedule. Objective: To explain how the introduction of DTaP-IPV/Hib in the NIP has changed vaccination practices for infants. Methods: Using a nationwide vaccine registry, the proportion of infants who completed the full recommended doses of the primary series of DTaP, IPV, and Hib (D-I-H) within 12 months of age was estimated among those born between 2013 and 2019. Among those, the proportions of those who received the same DTaP components for all 3 doses during the primary series were calculated for the 2013-2016 and the 2017-2019 birth cohorts. Those who received the same component of DTaP throughout the entire primary vaccination schedule were categorized into 3 groups by DTaP components to compare the average frequency of medical visits for vaccination. Results: A total of 2,703,822 infants were born between 2013 and 2019, of which 96.7% completed full doses of the primary D-I-H series within 12 months of age. For the 2013-2016 birth cohorts, most received DTaP-IPV-only (75.4%), while most of the 2017-2019 birth cohorts received DTaP-IPV/Hib-only (81.0%) to complete the 3 doses for primary D-I-H series. The average frequency of medical visits for vaccination showed a significant difference across the 3 groups classified by DTaP components in every birth cohort (p < 0.001). Conclusions: After the introduction of DTaP-IPV/Hib, most infants completed the primary D-I-H series with the combination vaccine and there was a significant reduction in the average number of medical visits for vaccination. Our findings provide important insights for countries considering the introduction of combination vaccines into their NIP.