1.Risk of Kawasaki Disease/Multisystem Inflammatory Syndrome Following COVID-19 Vaccination in Korean Children: A Self-Controlled Case Series Study
Suyeon KIM ; Hwa Yeon KO ; Jeongin OH ; Dongwon YOON ; Ju Hwan KIM ; Young June CHOE ; Ju-Young SHIN ; On behalf of the CoVaSC Investigators
Journal of Korean Medical Science 2025;40(3):e10-
		                        		
		                        			 Background:
		                        			Rare cases of Kawasaki disease (KD) and multisystem inflammatory syndrome in children (MIS-C) have been reported following the coronavirus disease 2019 (COVID-19) vaccination; however, the association between COVID-19 vaccination and the risk of developing KD/MIS-C has not yet been established. 
		                        		
		                        			Methods:
		                        			We conducted a self-controlled case series analysis using a large-linked database that connects the COVID-19 immunization registry with nationwide claims data. We identified individuals aged < 18 years who received their initial COVID-19 vaccination and had a KD/MIS-C diagnosis with a prescription for intravenous immunoglobulin or corticosteroids between October 18, 2021, and April 15, 2023. The observation period was set as 240 days from the date of the COVID-19 vaccination. The risk window was 60 days after vaccination, with the remaining observation period serving as the control window. The incidence rate ratios (IRRs) and 95% confidence intervals (CIs) in the risk versus control windows were estimated using the conditional Poisson regression model. We further analyzed the vaccine doses and types for secondary analysis. We also performed subgroup analyses stratified by sex, age, comorbidities, and other conditions and sensitivity analyses by varying the length of the risk window and outcome definition. 
		                        		
		                        			Results:
		                        			Among 2,369,490 individuals who received the COVID-19 vaccination, 12 cases of KD/MIS-C were identified, which included five and seven patients in the risk and control windows, respectively. There was no increased risk of KD/MIS-C within the 60-day period of vaccination (IRR, 0.53; 95% CI, 0.17–1.60). Secondary subgroup and sensitivity analyses showed no significant increase in the risk of KD/MIS-C after COVID-19 vaccination, which is consistent with the results of the main analysis. 
		                        		
		                        			Conclusion
		                        			The results of this nationwide study suggest that the risk of developing KD/MIS-C did not increase after COVID-19 vaccination. However, owing to the lack of a sufficient number of cases, future studies utilizing multinational long-term follow-up databases should be conducted. Considering the increasing incidence of KD/MIS-C and the limited understanding of its precise biological mechanisms, additional research on KD/MIS-C is warranted. 
		                        		
		                        		
		                        		
		                        	
2.Practicability of Suicide Reduction Target in Korean Suicide Prevention Policy: Insights From Time Series Analysis
Seunghyong RYU ; Seon-Hwa BAEK ; Min JHON ; Honey KIM ; Ju-Yeon LEE ; Jae-Min KIM ; Sung-Wan KIM
Journal of Korean Medical Science 2025;40(19):e59-
		                        		
		                        			 Background:
		                        			This study evaluated the practicability of the suicide rate reduction target set by the current national suicide prevention policy in Korea, the fifth Master Plan for Suicide Prevention (2023–2027). This policy aims to lower the suicide rate from 26/100,000 in 2021 to 18.2/100,000 by 2027. 
		                        		
		                        			Methods:
		                        			We utilized monthly suicide statistics data from 2011 onwards. Using Bayesian regression and Autoregressive Integrated Moving Average (ARIMA) models, we conducted interrupted time series analyses to estimate the effect of the previous policy, the National Action Plan for Suicide Prevention (2018–2022), on suicide rates. We assumed this as the additional suicide reduction expected from the current policy. We generated point predictions and simulations for suicide rates from 2023 to 2027 using Bayesian regression and ARIMA models. 
		                        		
		                        			Results:
		                        			The interrupted time series analyses did not reveal a significant reduction in suicides attributable to the previous policy. Point predictions from the two models indicated that the suicide rate would remain approximately 24/100,000 in 2027. Almost all of the simulations of the 2027 suicide rate did not meet the policy target of 18.2/100,000. 
		                        		
		                        			Conclusion
		                        			The findings suggest that the Korean government’s suicide rate reduction target for 2027 is likely unattainable based on current trends and the limited effectiveness of previous policies. The objectives of suicide prevention policies should be evidence-based, attainable, and accountable. 
		                        		
		                        		
		                        		
		                        	
3.Risk of Kawasaki Disease/Multisystem Inflammatory Syndrome Following COVID-19 Vaccination in Korean Children: A Self-Controlled Case Series Study
Suyeon KIM ; Hwa Yeon KO ; Jeongin OH ; Dongwon YOON ; Ju Hwan KIM ; Young June CHOE ; Ju-Young SHIN ; On behalf of the CoVaSC Investigators
Journal of Korean Medical Science 2025;40(3):e10-
		                        		
		                        			 Background:
		                        			Rare cases of Kawasaki disease (KD) and multisystem inflammatory syndrome in children (MIS-C) have been reported following the coronavirus disease 2019 (COVID-19) vaccination; however, the association between COVID-19 vaccination and the risk of developing KD/MIS-C has not yet been established. 
		                        		
		                        			Methods:
		                        			We conducted a self-controlled case series analysis using a large-linked database that connects the COVID-19 immunization registry with nationwide claims data. We identified individuals aged < 18 years who received their initial COVID-19 vaccination and had a KD/MIS-C diagnosis with a prescription for intravenous immunoglobulin or corticosteroids between October 18, 2021, and April 15, 2023. The observation period was set as 240 days from the date of the COVID-19 vaccination. The risk window was 60 days after vaccination, with the remaining observation period serving as the control window. The incidence rate ratios (IRRs) and 95% confidence intervals (CIs) in the risk versus control windows were estimated using the conditional Poisson regression model. We further analyzed the vaccine doses and types for secondary analysis. We also performed subgroup analyses stratified by sex, age, comorbidities, and other conditions and sensitivity analyses by varying the length of the risk window and outcome definition. 
		                        		
		                        			Results:
		                        			Among 2,369,490 individuals who received the COVID-19 vaccination, 12 cases of KD/MIS-C were identified, which included five and seven patients in the risk and control windows, respectively. There was no increased risk of KD/MIS-C within the 60-day period of vaccination (IRR, 0.53; 95% CI, 0.17–1.60). Secondary subgroup and sensitivity analyses showed no significant increase in the risk of KD/MIS-C after COVID-19 vaccination, which is consistent with the results of the main analysis. 
		                        		
		                        			Conclusion
		                        			The results of this nationwide study suggest that the risk of developing KD/MIS-C did not increase after COVID-19 vaccination. However, owing to the lack of a sufficient number of cases, future studies utilizing multinational long-term follow-up databases should be conducted. Considering the increasing incidence of KD/MIS-C and the limited understanding of its precise biological mechanisms, additional research on KD/MIS-C is warranted. 
		                        		
		                        		
		                        		
		                        	
4.Practicability of Suicide Reduction Target in Korean Suicide Prevention Policy: Insights From Time Series Analysis
Seunghyong RYU ; Seon-Hwa BAEK ; Min JHON ; Honey KIM ; Ju-Yeon LEE ; Jae-Min KIM ; Sung-Wan KIM
Journal of Korean Medical Science 2025;40(19):e59-
		                        		
		                        			 Background:
		                        			This study evaluated the practicability of the suicide rate reduction target set by the current national suicide prevention policy in Korea, the fifth Master Plan for Suicide Prevention (2023–2027). This policy aims to lower the suicide rate from 26/100,000 in 2021 to 18.2/100,000 by 2027. 
		                        		
		                        			Methods:
		                        			We utilized monthly suicide statistics data from 2011 onwards. Using Bayesian regression and Autoregressive Integrated Moving Average (ARIMA) models, we conducted interrupted time series analyses to estimate the effect of the previous policy, the National Action Plan for Suicide Prevention (2018–2022), on suicide rates. We assumed this as the additional suicide reduction expected from the current policy. We generated point predictions and simulations for suicide rates from 2023 to 2027 using Bayesian regression and ARIMA models. 
		                        		
		                        			Results:
		                        			The interrupted time series analyses did not reveal a significant reduction in suicides attributable to the previous policy. Point predictions from the two models indicated that the suicide rate would remain approximately 24/100,000 in 2027. Almost all of the simulations of the 2027 suicide rate did not meet the policy target of 18.2/100,000. 
		                        		
		                        			Conclusion
		                        			The findings suggest that the Korean government’s suicide rate reduction target for 2027 is likely unattainable based on current trends and the limited effectiveness of previous policies. The objectives of suicide prevention policies should be evidence-based, attainable, and accountable. 
		                        		
		                        		
		                        		
		                        	
5.Risk of Kawasaki Disease/Multisystem Inflammatory Syndrome Following COVID-19 Vaccination in Korean Children: A Self-Controlled Case Series Study
Suyeon KIM ; Hwa Yeon KO ; Jeongin OH ; Dongwon YOON ; Ju Hwan KIM ; Young June CHOE ; Ju-Young SHIN ; On behalf of the CoVaSC Investigators
Journal of Korean Medical Science 2025;40(3):e10-
		                        		
		                        			 Background:
		                        			Rare cases of Kawasaki disease (KD) and multisystem inflammatory syndrome in children (MIS-C) have been reported following the coronavirus disease 2019 (COVID-19) vaccination; however, the association between COVID-19 vaccination and the risk of developing KD/MIS-C has not yet been established. 
		                        		
		                        			Methods:
		                        			We conducted a self-controlled case series analysis using a large-linked database that connects the COVID-19 immunization registry with nationwide claims data. We identified individuals aged < 18 years who received their initial COVID-19 vaccination and had a KD/MIS-C diagnosis with a prescription for intravenous immunoglobulin or corticosteroids between October 18, 2021, and April 15, 2023. The observation period was set as 240 days from the date of the COVID-19 vaccination. The risk window was 60 days after vaccination, with the remaining observation period serving as the control window. The incidence rate ratios (IRRs) and 95% confidence intervals (CIs) in the risk versus control windows were estimated using the conditional Poisson regression model. We further analyzed the vaccine doses and types for secondary analysis. We also performed subgroup analyses stratified by sex, age, comorbidities, and other conditions and sensitivity analyses by varying the length of the risk window and outcome definition. 
		                        		
		                        			Results:
		                        			Among 2,369,490 individuals who received the COVID-19 vaccination, 12 cases of KD/MIS-C were identified, which included five and seven patients in the risk and control windows, respectively. There was no increased risk of KD/MIS-C within the 60-day period of vaccination (IRR, 0.53; 95% CI, 0.17–1.60). Secondary subgroup and sensitivity analyses showed no significant increase in the risk of KD/MIS-C after COVID-19 vaccination, which is consistent with the results of the main analysis. 
		                        		
		                        			Conclusion
		                        			The results of this nationwide study suggest that the risk of developing KD/MIS-C did not increase after COVID-19 vaccination. However, owing to the lack of a sufficient number of cases, future studies utilizing multinational long-term follow-up databases should be conducted. Considering the increasing incidence of KD/MIS-C and the limited understanding of its precise biological mechanisms, additional research on KD/MIS-C is warranted. 
		                        		
		                        		
		                        		
		                        	
6.Practicability of Suicide Reduction Target in Korean Suicide Prevention Policy: Insights From Time Series Analysis
Seunghyong RYU ; Seon-Hwa BAEK ; Min JHON ; Honey KIM ; Ju-Yeon LEE ; Jae-Min KIM ; Sung-Wan KIM
Journal of Korean Medical Science 2025;40(19):e59-
		                        		
		                        			 Background:
		                        			This study evaluated the practicability of the suicide rate reduction target set by the current national suicide prevention policy in Korea, the fifth Master Plan for Suicide Prevention (2023–2027). This policy aims to lower the suicide rate from 26/100,000 in 2021 to 18.2/100,000 by 2027. 
		                        		
		                        			Methods:
		                        			We utilized monthly suicide statistics data from 2011 onwards. Using Bayesian regression and Autoregressive Integrated Moving Average (ARIMA) models, we conducted interrupted time series analyses to estimate the effect of the previous policy, the National Action Plan for Suicide Prevention (2018–2022), on suicide rates. We assumed this as the additional suicide reduction expected from the current policy. We generated point predictions and simulations for suicide rates from 2023 to 2027 using Bayesian regression and ARIMA models. 
		                        		
		                        			Results:
		                        			The interrupted time series analyses did not reveal a significant reduction in suicides attributable to the previous policy. Point predictions from the two models indicated that the suicide rate would remain approximately 24/100,000 in 2027. Almost all of the simulations of the 2027 suicide rate did not meet the policy target of 18.2/100,000. 
		                        		
		                        			Conclusion
		                        			The findings suggest that the Korean government’s suicide rate reduction target for 2027 is likely unattainable based on current trends and the limited effectiveness of previous policies. The objectives of suicide prevention policies should be evidence-based, attainable, and accountable. 
		                        		
		                        		
		                        		
		                        	
7.Risk of Kawasaki Disease/Multisystem Inflammatory Syndrome Following COVID-19 Vaccination in Korean Children: A Self-Controlled Case Series Study
Suyeon KIM ; Hwa Yeon KO ; Jeongin OH ; Dongwon YOON ; Ju Hwan KIM ; Young June CHOE ; Ju-Young SHIN ; On behalf of the CoVaSC Investigators
Journal of Korean Medical Science 2025;40(3):e10-
		                        		
		                        			 Background:
		                        			Rare cases of Kawasaki disease (KD) and multisystem inflammatory syndrome in children (MIS-C) have been reported following the coronavirus disease 2019 (COVID-19) vaccination; however, the association between COVID-19 vaccination and the risk of developing KD/MIS-C has not yet been established. 
		                        		
		                        			Methods:
		                        			We conducted a self-controlled case series analysis using a large-linked database that connects the COVID-19 immunization registry with nationwide claims data. We identified individuals aged < 18 years who received their initial COVID-19 vaccination and had a KD/MIS-C diagnosis with a prescription for intravenous immunoglobulin or corticosteroids between October 18, 2021, and April 15, 2023. The observation period was set as 240 days from the date of the COVID-19 vaccination. The risk window was 60 days after vaccination, with the remaining observation period serving as the control window. The incidence rate ratios (IRRs) and 95% confidence intervals (CIs) in the risk versus control windows were estimated using the conditional Poisson regression model. We further analyzed the vaccine doses and types for secondary analysis. We also performed subgroup analyses stratified by sex, age, comorbidities, and other conditions and sensitivity analyses by varying the length of the risk window and outcome definition. 
		                        		
		                        			Results:
		                        			Among 2,369,490 individuals who received the COVID-19 vaccination, 12 cases of KD/MIS-C were identified, which included five and seven patients in the risk and control windows, respectively. There was no increased risk of KD/MIS-C within the 60-day period of vaccination (IRR, 0.53; 95% CI, 0.17–1.60). Secondary subgroup and sensitivity analyses showed no significant increase in the risk of KD/MIS-C after COVID-19 vaccination, which is consistent with the results of the main analysis. 
		                        		
		                        			Conclusion
		                        			The results of this nationwide study suggest that the risk of developing KD/MIS-C did not increase after COVID-19 vaccination. However, owing to the lack of a sufficient number of cases, future studies utilizing multinational long-term follow-up databases should be conducted. Considering the increasing incidence of KD/MIS-C and the limited understanding of its precise biological mechanisms, additional research on KD/MIS-C is warranted. 
		                        		
		                        		
		                        		
		                        	
8.Practicability of Suicide Reduction Target in Korean Suicide Prevention Policy: Insights From Time Series Analysis
Seunghyong RYU ; Seon-Hwa BAEK ; Min JHON ; Honey KIM ; Ju-Yeon LEE ; Jae-Min KIM ; Sung-Wan KIM
Journal of Korean Medical Science 2025;40(19):e59-
		                        		
		                        			 Background:
		                        			This study evaluated the practicability of the suicide rate reduction target set by the current national suicide prevention policy in Korea, the fifth Master Plan for Suicide Prevention (2023–2027). This policy aims to lower the suicide rate from 26/100,000 in 2021 to 18.2/100,000 by 2027. 
		                        		
		                        			Methods:
		                        			We utilized monthly suicide statistics data from 2011 onwards. Using Bayesian regression and Autoregressive Integrated Moving Average (ARIMA) models, we conducted interrupted time series analyses to estimate the effect of the previous policy, the National Action Plan for Suicide Prevention (2018–2022), on suicide rates. We assumed this as the additional suicide reduction expected from the current policy. We generated point predictions and simulations for suicide rates from 2023 to 2027 using Bayesian regression and ARIMA models. 
		                        		
		                        			Results:
		                        			The interrupted time series analyses did not reveal a significant reduction in suicides attributable to the previous policy. Point predictions from the two models indicated that the suicide rate would remain approximately 24/100,000 in 2027. Almost all of the simulations of the 2027 suicide rate did not meet the policy target of 18.2/100,000. 
		                        		
		                        			Conclusion
		                        			The findings suggest that the Korean government’s suicide rate reduction target for 2027 is likely unattainable based on current trends and the limited effectiveness of previous policies. The objectives of suicide prevention policies should be evidence-based, attainable, and accountable. 
		                        		
		                        		
		                        		
		                        	
9.Changes in Suicide Rate Trend After Implementation of Suicide Prevention Policy: An Interrupted Time Series Study on the Fifth Master Plan for Suicide Prevention
Seunghyong RYU ; Seon-Hwa BAEK ; Min JHON ; Honey KIM ; Ju-Yeon LEE ; Jae-Min KIM ; Sung-Wan KIM
Journal of Korean Neuropsychiatric Association 2024;63(4):237-245
		                        		
		                        			 Objectives:
		                        			This study examined the shifts in the suicide trends in Korea during the initial phase of the Fifth Master Plan for Suicide Prevention, using interrupted time series analyses. 
		                        		
		                        			Methods:
		                        			Interrupted time series analyses were performed using the monthly suicide data from January 2011 to April 2024. Quasi-Poisson regression models were applied to evaluate the changes in the level and slope of the suicide trend before and after policy implementation. The Autoregressive Integrated Moving Average (ARIMA) and Prophet models were used to compare the actual and predicted counterfactual numbers of suicides during the policy period. 
		                        		
		                        			Results:
		                        			The quasi-Poisson regression model revealed a significant change in the trend of suicides among men, with an increasing slope during the policy period. For total suicides, the ARIMA and Prophet models suggested that the actual number of suicides was significantly higher than the counterfactual number during the policy period, with excess suicides averaging between 113 and 150 per month. The actual number of suicides among men was significantly higher than the counterfactual number during the policy period, with excess suicides averaging between 86 and 92 per month. No significant changes in the suicide trends among women were observed. 
		                        		
		                        			Conclusion
		                        			These findings suggest that the initial effects of the Fifth Master Plan for Suicide Prevention were inadequate to curb the rising suicide trends, particularly among men. This study underscores the need for timely policy responses to reverse the current increasing trend in suicides, with particular focus on the male population. 
		                        		
		                        		
		                        		
		                        	
10.Association between mechanical power and intensive care unit mortality in Korean patients under pressure-controlled ventilation
Jae Kyeom SIM ; Sang-Min LEE ; Hyung Koo KANG ; Kyung Chan KIM ; Young Sam KIM ; Yun Seong KIM ; Won-Yeon LEE ; Sunghoon PARK ; So Young PARK ; Ju-Hee PARK ; Yun Su SIM ; Kwangha LEE ; Yeon Joo LEE ; Jin Hwa LEE ; Heung Bum LEE ; Chae-Man LIM ; Won-Il CHOI ; Ji Young HONG ; Won Jun SONG ; Gee Young SUH
Acute and Critical Care 2024;39(1):91-99
		                        		
		                        			
		                        			 Mechanical power (MP) has been reported to be associated with clinical outcomes. Because the original MP equation is derived from paralyzed patients under volume-controlled ventilation, its application in practice could be limited in patients receiving pressure-controlled ventilation (PCV). Recently, a simplified equation for patients under PCV was developed. We investigated the association between MP and intensive care unit (ICU) mortality. Methods: We conducted a retrospective analysis of Korean data from the Fourth International Study of Mechanical Ventilation. We extracted data of patients under PCV on day 1 and calculated MP using the following simplified equation: MPPCV = 0.098 ∙ respiratory rate ∙ tidal volume ∙ (ΔPinsp + positive end-expiratory pressure), where ΔPinsp is the change in airway pressure during inspiration. Patients were divided into survivors and non-survivors and then compared. Multivariable logistic regression was performed to determine association between MPPCV and ICU mortality. The interaction of MPPCV and use of neuromuscular blocking agent (NMBA) was also analyzed. Results: A total of 125 patients was eligible for final analysis, of whom 38 died in the ICU. MPPCV was higher in non-survivors (17.6 vs. 26.3 J/min, P<0.001). In logistic regression analysis, only MPPCV was significantly associated with ICU mortality (odds ratio, 1.090; 95% confidence interval, 1.029–1.155; P=0.003). There was no significant effect of the interaction between MPPCV and use of NMBA on ICU mortality (P=0.579). Conclusions: MPPCV is associated with ICU mortality in patients mechanically ventilated with PCV mode, regardless of NMBA use.  
		                        		
		                        		
		                        		
		                        	
            
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