A framework for nationwide COVID-19 vaccine safety research in the Republic of Korea: the COVID-19 Vaccine Safety Research Committee

With the introduction of coronavirus disease 2019 (COVID-19) vaccines, the Korea Disease Control and Prevention Agency (KDCA) commissioned the National Academy of Medicine of Korea to gather experts to independently assess post-vaccination adverse events. Accordingly, the COVID-19 Vaccine Safety Research Committee (CoVaSC) was launched in November 2021 to perform safety studies and establish evidence for policy guidance. The CoVaSC established 3 committees for epidemiology, clinical research, and communication. The CoVaSC mainly utilizes pseudonymized data linking KDCA’s COVID-19 vaccination data and the National Health Insurance Service’s claims data. The CoVaSC’s 5-step research process involves defining the target diseases and organizing ad-hoc committees, developing research protocols, performing analyses, assessing causal relationships, and announcing research findings and utilizing them to guide compensation policies. As of 2022, the CoVaSC completed this research process for 15 adverse events. The CoVaSC launched the COVID-19 Vaccine Safety Research Center in September 2022 and has been reorganized into 4 divisions to promote research including international collaborative studies, long-/short-term follow-up studies, and education programs. Through these enhancements, the CoVaSC will continue to swiftly provide scientific evidence for COVID-19 vaccine research and compensation and may serve as a model for preparing for future epidemics of new diseases.

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.

Short-term safety profile of COVID-19 vaccination in children and adolescents with underlying medical conditions: a prospective cohort study

Purpose@#This article was to collect data on the safety of coronavirus disease 2019 (COVID-19) vaccines in children with underlying medical conditions. @*Methods@#We constructed a prospective cohort of children and adolescents aged 5 to 19 years who had received at least one dose of COVID-19 vaccine. Patients diagnosed with and treated for chronic kidney disease, autoimmune disease, or other chronic conditions at the Seoul National University Children’s Hospital were recruited from June to December 2022. A mobile survey questionnaire was sent to their guardians. The presence of adverse events on the day (day 0), 3 weeks (day 21), and 6 months (day 180) after the 1st dose of COVID-19 vaccine was recorded by the guardians. @*Results@#A total of 73 children participated. The median age was 14 years, and 64.4% of the patients were male. On the day of immunization, 65.8% of the patients reported at least one adverse event. Pain at the injection site, fatigue, headache, arthralgia, and myalgia were the most common symptoms. The prevalence of adverse events decreased over time (65.8% on day 0, 27.4% between days 0 and 21, and 24.6% between days 21 and 180). Severe acute respiratory syndrome coronavirus 2 infection after the 1st dose occurred in 17 patients (23.3%) and one of the patients (5.88%) was hospitalized due to infection. @*Conclusions@#Adverse events after COVID-19 vaccination were generally mild in children and adolescents with underlying medical conditions. Our findings provide evidence for the safety of COVID-19 vaccination in the vulnerable pediatric population.

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 casecrossover 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.

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 casecrossover 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.

Levothyroxine Dose and Fracture Risk According to the Osteoporosis Status in Elderly Women / 예방의학회지

OBJECTIVES: To evaluate the association between fracture risk and levothyroxine use in elderly women with hypothyroidism, according to previous osteoporosis history. METHODS: We conducted a cohort study from the Korean Health Insurance Review and Assessment Service claims database from January 2005 to June 2006. The study population comprised women aged > or =65 years who had been diagnosed with hypothyroidism and prescribed levothyroxine monotherapy. We excluded patients who met any of the following criteria: previous fracture history, hyperthyroidism, thyroid cancer, or pituitary disorder; low levothyroxine adherence; or a follow-up period 150 microg/d. The hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated with the Cox proportional hazard model, and subgroup analyses were performed according to the osteoporosis history and osteoporosis-specific drug prescription status. RESULTS: Among 11 155 cohort participants, 35.6% had previous histories of osteoporosis. The adjusted HR of fracture for the >150 microg/d group, compared with the 51 to 100 microg/d group, was 1.56 (95% CI, 1.03 to 2.37) in osteoporosis subgroup. In the highly probable osteoporosis subgroup, restricted to patients who were concurrently prescribed osteoporosis-specific drugs, the adjusted HR of fracture for the >150 microg/d group, compared with the 51 to 100 microg/d group, was 1.93 (95% CI, 1.14 to 3.26). CONCLUSIONS: While further studies are needed, physicians should be concerned about potential levothyroxine overtreatment in elderly osteoporosis 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.

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.

Use of big data for drug safety monitoring and decision making

The development of information technologies has led to the era of big data; such enormous collections of information on drugs and adverse drug reactions are stored in either a structured, a semistructured, or an unstructured form. Because of the nature of the emerging issue of drug safety, it is common for policy makers and healthcare professionals to make decisions without sufficient evidence. Big data may be used as an efficient pharmacovigilance tool, which enables us to recognize adverse drug reactions that may not have been identified in pre-marketing clinical trials, in order to capture the patterns of drug utilization and adverse events, and to predict the occurrence of adverse drug reactions. National surveillance systems using electronic health databases have been established successfully in the US and Europe. The Korea Institute of Drug Safety and Risk Management (KIDS) plans to establish a big data platform for pharmacovigilance in Korea. The big data may be effectively used for evidence-based regulatory and clinical decision making in the field of drug safety and risk management.

Comparison of the Safety of Seven Iodinated Contrast Media

We aimed to determine the characteristic adverse events (AEs) of iodinated contrast media (IOCM) and to compare the safety profiles of different IOCM. This study used the database of AEs reports submitted by healthcare professionals from 15 Regional Pharmacovigilance Centers between June 24, 2009 and December 31, 2010 in Korea. All reports of IOCM, including iopromide, iohexol, iopamidol, iomeprol, ioversol, iobitridol and iodixanol, were analyzed. Safety profiles were compared between different IOCM at the system organ level using the proportional reporting ratio (PRR) and 95% confidence interval (95% CI). Among a total of 48,261 reports, 6,524 (13.5%) reports were related to the use of IOCM. Iopromide (45.5%), iohexol (16.9%), iopamidol (14.3%) and iomeprol (10.3%) were identified as frequently reported media. 'Platelet, bleeding & clotting disorders' (PRR, 29.6; 95%CI, 1.9-472.6) and 'urinary system disorders' (PRR, 22.3; 95% CI, 17.1-29.1) were more frequently reported for iodixanol than the other IOCM. In conclusion, the frequency of AEs by organ class was significantly different between individual media. These differences among different IOCM should be considered when selecting a medium among various IOCM and when monitoring patients during and after its use to ensure optimum usage and patient safety.

Zolpidem Use and Risk of Fracture in Elderly Insomnia Patients / 예방의학회지

OBJECTIVES: To evaluate the risk of fractures related with zolpidem in elderly insomnia patients. METHODS: Health claims data on the entire South Korean elderly population from January 2005 to June 2006 were extracted from the Health Insurance Review and Assessment Service database. We applied a case-crossover design. Cases were defined as insomnia patients who had a fracture diagnosis. We set the hazard period of 1 day length prior to the fracture date and four control periods of the same length at 5, 10, 15, and 20 weeks prior to the fracture date. Time independent confounding factors such as age, gender, lifestyle, cognitive function level, mobility, socioeconomic status, residential environment, and comorbidity could be controlled using the casecrossover design. Time dependent confounding factors, especially co-medication of patients during the study period, were adjusted by conditional logistic regression analysis. The odds ratios and their 95% confidence intervals (CIs) were estimated for the risk of fracture related to zolpidem. RESULTS: One thousand five hundred and eight cases of fracture were detected in insomnia patients during the study period. In our data, the use of zolpidem increased the risk of fracture significantly (adjusted odds ratio [aOR], 1.72; 95% CI, 1.37 to 2.16). However, the association between benzodiazepine hypnotics and the risk of fracture was not statistically significant (aOR, 1.00; 95% CI, 0.83 to 1.21). Likewise, the results were not statistically significant in stratified analysis with each benzodiazepine generic subgroup. CONCLUSIONS: Zolpidem could increase the risk of fracture in elderly insomnia patients. Therefore zolpidem should be prescribed carefully and the elderly should be provided with sufficient patient education.

Prevalence Rate and Associated Factors of Sarcopenic Obesity in Korean Elderly Population

This study was conducted to estimate the prevalence rates and to explore associated factors of sarcopenic obesity (SO) in 2,221 Koreans over 60 yr-of age from the Fourth Korea National Health and Nutrition Examination Survey (2009). Participants were assessed by dual energy X-ray absorptiometry. Appendicular skeletal muscle mass divided by body weight was used to define sarcopenia and waist circumference was used to define obesity. We estimated the prevalence rates of SO according to age-groups, sex and region. In addition, each group was compared by demographic characteristics, metabolic status, nutrition, and physical activity. The prevalence rates of SO were 6.1% (95% confidential interval [CI] = 6.1-6.2) for men and 7.3% (95% CI = 7.3-7.3) for women, respectively. SO was positively associated with no current working and the number of combined medical conditions. High serum insulin level was positively associated with SO, whereas vitamin D was negatively associated with SO in both men and women. In conclusion, the prevalence rates of SO are 6.1% in men and 7.3% in women. SO is associated with insulin resistance, inappropriate nutrition, and low physical activity.

Recent international initiatives of drug safety management

Adverse drug reactions constitute a major public health problem. In recent years, serious safety issues arose with marketed drugs, and public outcry demanded better safety surveillance. Now regulatory focus is shifting to the active post-marketing safety surveillance. This paper provides an overview of the recent international initiatives of drug safety management especially focused on the US and Europe. The US Food and Drug Administration's (FDA) Sentinel Initiative is a long-term program designed to build and implement a national electronic system for monitoring the safety of FDA-approved drugs and other medical products. The Sentinel System will enable FDA to monitor the safety of medical products with the assistance of a wide array of collaborating institutions throughout the nation. The European Network of Centers for Pharmacoepidemiology and Pharmacovigilance is a collaborative scientific network coordinated by the European Medicines Agency and developed in collaboration with European experts in the fields of pharmacoepidemiology and pharmacovigilance. Its goal is to further strengthen the post-marketing monitoring of medicinal products in Europe by facilitating the conduct of multi-center, independent, post-authorization studies focusing on safety and on benefit-risk. Medicine is a global enterprise that demands worldwide standards for good drug safety practices. In the near future, we have to establish a Korean Sentinel System for active post-marketing safety surveillance to ensure the safety and effectiveness of drugs used in medical practice.

Overlapping Medication Associated with Healthcare Switching among Korean Elderly Diabetic Patients

This study was performed to describe the patterns of healthcare switching with overlapping use of anti-diabetic medication in the elderly using the Korea Health Insurance Review and Assessment Service's claims data. The study subjects were ambulatory elderly diabetic patients (ICD-10, E10-14) receiving at least one oral anti-diabetic drug or insulin, and visiting healthcare facilities more than two times between January and December 2005. A total of 457,975 elderly diabetic ambulatory care patients were identified. The mean of visiting frequencies was 9.0 ( +/- 3.6) and switching frequencies was 1.5 ( +/- 0.8) during 2005. Switching group consisted of 33% of total study subject. Healthcare switching was common in female patients who were older, and had treated polytherapy more in rural areas. The movement among primary care medical services was very common among the patients in the switching group (52.6%). A statistically significant correlation was observed between the healthcare switching and concomitant drug use (rho = 0.96), and overlapping days (rho = 0.57). The use of overlapping anti-diabetic medication increased with the extent of healthcare switching. Further, frequent switching of healthcare between primary clinics was observed. Efforts should be made to establish continuity for the elderly diabetic patients with the identification of frequent switching with overlapping medication.

Risk Factors for New Onset Diabetes after Transplantation among Renal Transplant Recipients Treated with Tacrolimus / 대한신장학회지

PURPOSE: This study was conducted to identify risk factors for new onset diabetes after transplantation (NODAT) among renal transplant recipients treated with tacrolimus-based immunosuppressant. METHODS: We selected renal transplant recipients who underwent surgery at Samsung Seoul Hospital between May 2001 and July 2009. Exclusion criteria were as follows: recipients years: RR=4.36, 95% CI 2.00-9.49), family history of DM (RR=1.62, 95% CI 1.12-2.34) and polyomavirus infection (RR=1.40, 95% CI 1.08-1.81). CONCLUSION: The risk factors for NODAT among renal transplant recipients treated with tacrolimus-based regimen were age (>45 years old), family history of DM and polyomavirus infection.

Strategy for establishing an effective Korean drug utilization review system

Drug utilization review (DUR) system has been defined as "structured, ongoing initiatives that interpret patterns of drug use in relation to predetermined criteria, and attempt to prevent or minimize inappropriate prescribing." This paper introduces the concept, purpose, and effective application of DUR in Korea. DUR can be classified as retrospective DUR, prospective DUR, and concurrent DUR based on the time direction of applying DUR. DUR can also be classified as quantitative DUR defined by retrospective DUR using databases including previously prescribed medicines, and qualitative DUR defined by DUR reflecting patient's clinical condition. We described the history of developing DUR in the United States and the Europe. Finally current status of DUR in Korea is described and the strategy of future settlement of DUR system in Korea is suggested.

Co-prescribing Patterns of Contraindicated Drugs for the Elderly Patients in Busan / 한국역학회지

PURPOSE: To estimate the prevalence of co-prescribing contraindicated drugs for elderly patients in Busan. METHODS: We used the Health Insurance Review Agency (HIRA) claims database. Study population consisted of elderly patients who visited clinics or hospitals in Busan metropolitan city from January 1, 2000 to December 31, 2001. Contraindicated drugs were defined as 162 combinations of contraindicated drugs announced by the Korea Ministry of Health and Welfare in 2004. The co-prescription of contraindicated drugs was defined as prescribing two or more contraindicated drugs in combination in the same prescription. The prevalence of co-prescribing contraindicated drugswas estimated as proportion of co-prescribed patients out of the study patients. We estimated and age-adjusted prevalence and its 95% confidence interval of co-prescription of contraindicated drugs among the elderly patients in Korean population in 2001. RESULTS: The study elderly patients were 262,952 with 2,483,227 prescriptions. Among the study patients 1,208 (4.6%) were prescribed contraindicated drugs in combination. A total of 16,255 patients were estimated as the number of co-prescribed patients among the Korean elderly in 2001. Age-standardized prevalence of co-prescription to the Korean elderly was estimated to be 45 per 10,000 persons. The most frequently prescribed combinations were cisapride & amitriptyline, roxithromycin & ergoloid mesylate, and terfenadine & erythromycin, and the frequency were 325 (16.8%), 149 (7.7%), and 132 (6.8%),respectively. CONCLUSIONS: The contraindicated drugs were co-prescribed to the elderly patients in Korea. Many of these co-prescriptions should be avoided if unnecessary. The patients should be carefully monitored if they were inevitably prescribed the contraindicated drugs.

Adverse Drug Reaction Surveillance System in Korea / 예방의학회지

Despite extensive researches and pre-market clinical trials, only limited information on the adverse drug reactions (ADRs) of a drug can be collected at the time of market approval from regulatory agency. ADRs constitute a major public health problem. Post-marketing surveillance of drugs is important to detect signals for ADR. In Korea, one of the main methods for monitoring the safety of marketed drugs is spontaneous reporting system of suspected ADRs. Re-examination and re-evaluation system are in force for monitoring safety of new market approval drugs and currently under marketing drugs, respectively. Recently, regional pharmacovigilance centers were designated from Korean Food and Drug Administration for facilitating ADR surveillance. Over recent years, with the development of information technology, there has been an increased interest in establishing data mining system for detecting signals from Health Insurance Review Agency database. The purpose of this paper is to review the current status of Korean ADR surveillance system and suggest the possible solutions for developing active pharmacovigilance system in Korea.

Adverse Drug Reaction Surveillance and the Role of Family Physicians

No abstract available.

Natural Menopause and Risk of Stroke in Elderly Women

Although early natural menopause has been postulated to increase stroke risk, studies have not produced convincing results. We examined the associations between stroke risks and age at natural menopause or time since natural menopause. 5,731 naturally postmenopausal women more than 65 yr of age were followed from 1993 to 1998. Information on age at menopause and risk factors were obtained using mailed questionnaires. 186 cases of stroke occurred over a total 27,936 person years. After adjusting for age, hypertension, and physical activity, age at menopause was not found to be significantly associated with stroke or cerebral infarction. However, adjusted relative risks (aRRs) showed a significant increasing tendency of hemorrhagic stroke versus age at menopause (aRRs, 0.66, 0.48, 1.00 and 2.33 for the following age groups at menopause; 40-44, 45-49, 50-54 [reference group], and > or =55 yr). Time since menopause (11-20, 21-30, and > or =31 yr) was not found to be significantly associated with cerebral infarction, or hemorrhagic stroke. Late menopause (menopause age > or =55 yr) showed a tendency of a lower risk of cerebral infarction (aRR, 0.79) and a higher risk of hemorrhagic stroke (aRR, 2.33). Further study is warranted to determine stroke risk in women during the decade following menopause.