• Health Policy and Management
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• v.28 no.1
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• pp.87-90
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• 2018

Suicide has been a public health issue in many countries, and Korea has ranked highest suicide rate among Organization for Economic Cooperation and Development (OECD) countries over a decade. To address these issues, we updated the recent trends in suicidal ideation and suicide attempts among Korean adults followed by previous data observation. We used data from five sources: Korean National Health and Nutrition Examination (KNHANES, '07-12, '13, '15-16), Korean Community Health Survey (KCHS, '08-09, '13), Korean Wealth Panel Study (KOWEPS, '12-16), Korea Health Panel Survey (KHP, '10-13), and cause of death data from Statistics Korea ('07-16). We used weighted frequencies and trend tests. The rate of suicidal ideation as recent year was 5.10% (KNHANES, '15), 8.95% (KCHS, '13), 2.08% (KOWEPS, '16), and 5.39% (KHP, '13). That of suicide attempts as recent year was 0.59% (KNHANES, '16), 0.41% (KCHS, '13), and 0.08% (KOWEPS, '16). Annual percentage change of suicidal ideation was -2.80% (KNHANES, '07-12), 5.78% (KNHANES, '13-15), 0.62% (KCHS, '08-13), -8.50% (KOWEPS, '12-16), and -10.94% (KHP, '10-13). Annual percentage change of suicide attempts was -3.84% (KNHANES, '07-12), 2.26% (KNHANES, '13-16), -2.53% (KCHS, '08-13), and -20.22% (KOWEPS, '12-16). Annual percentage change of death by intentional self-harm was -0.49% (Statistics Korea, '07-16). Individuals who had lower income level were more likely to experience suicidal ideation and suicide attempts. According to these results, the rate of suicidal ideation and suicide attempts showed the decreasing tendency. However, the suicide rate of Korea has remained higher than that of OECD countries. Thus, continuous data observation and effective policies on suicide are needed.

• Journal of Environmental Health Sciences
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• v.43 no.4
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• pp.298-306
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• 2017

Objectives: Since 1998, the Korea National Health and Nutrition Examination Survey (KNHANES) has been conducted in order to investigate the health and nutritional status of Koreans. The food intake data of individuals in the KNHANES has also been utilized as source dataset for risk assessment of chemicals via food. To improve the reliability of intake estimation and prevent missing data for less-responded foods, the structure of integrated long-standing datasets is significant. However, it is difficult to merge multi-year survey datasets due to ineffective cleaning processes for handling extensive numbers of codes for each food item along with changes in dietary habits over time. Therefore, this study aims at 1) cleaning the process of abnormal data 2) generation of integrated long-standing raw data, and 3) contributing to the production of consistent dietary exposure factors. Methods: Codebooks, the guideline book, and raw intake data from KNHANES V and VI were used for analysis. The violation of the primary key constraint and the $1^{st}-3rd$ normal form in relational database theory were tested for the codebook and the structure of the raw data, respectively. Afterwards, the cleaning process was executed for the raw data by using these integrated codes. Results: Duplication of key records and abnormality in table structures were observed. However, after adjusting according to the suggested method above, the codes were corrected and integrated codes were newly created. Finally, we were able to clean the raw data provided by respondents to the KNHANES survey. Conclusion: The results of this study will contribute to the integration of the multi-year datasets and help improve the data production system by clarifying, testing, and verifying the primary key, integrity of the code, and primitive data structure according to the database normalization theory in the national health data.

• Korean Journal of Community Nutrition
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• v.27 no.3
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• pp.245-253
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• 2022

Objectives: This study was conducted to find out if the dietary iron intake of Koreans estimated by 2 different methods (iron content sources) using the food intake data from the Korea National Health and Nutrition Examination Survey (KNHANES) are comparable. One method was based on the KNHANES's Food & Nutrient Database (FND) derived mainly from the Korean Food Composition Table and the other used the iron content (IC) of food samples processed in the Korean Total Diet Study (KTDS). Methods: Dietary intake data from the 2013-2016 KNHANES was used to select representative foods (RFs) in KTDS for iron analysis. Selection of the RFs and cooking methods for each RF (RF × cooking method pair) was performed according to the 'Guidebook for Korean Total Diet Studies' and resulted in a total of 132 RFs and 224 'RF × cooking method' pairs. RFs were collected in 9 metropolitan cities nationwide once or twice (for those with seasonality) in 2018 and made into 6 composites each, based on the origin and season prior to cooking. Then, the RF composites prepared to a 'table ready' state for KTDS were analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Dietary iron intake of the Korean population was estimated using only RFs' intake data based on the 2 sources of iron content, namely FND-KNHANES and IC-KTDS. Results: RFs in KTDS covered 92.0% of total food intake of Koreans in the 2016-2018 KNHANES. Mean iron intake of Koreans was 7.77 mg/person/day by IC-KTDS vs 9.73 mg/person/day by FND-KNHANES. The major food groups contributing to iron intake were meats (21.7%), vegetables (20.5%), and grains & cereals (13.4%) as per IC-KTDS. On the other hand, the latter source (FND-KNHANES) resulted in a very different profile: grains & cereals (31.1%), vegetables (16.8%), and meats (15.3%). While the top iron source was beef, accounting for 8.6% in the former, it was polished rice (19.2%) in the latter. There was a 10-fold difference in the iron content of polished rice between 2 sources that iron intakes excluding the contribution by polished rice resulted in very similar values: 7.58 mg/person/day by IC-KTDS and 7.86 mg/person/day by FND-KNHANES. Conclusions: This study revealed that the dietary iron intake estimated by 2 different methods were quite comparable, excluding one RF, namely polished rice. KTDS was thus proven to be a useful tool in estimating a 'closer-to-real' dietary intake of nutrients for Koreans and further research on various nutrients is warranted.

• Honam Mathematical Journal
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• v.43 no.4
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• pp.717-739
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• 2021

We used blood data to predict obesity by complementing the BMI risk, because some blood factors are significantly associated with obesity. For the sampling method, a two-step stratified colony sampling method was used based on sixteen blood factors collected by the Korea National Health and Nutrition Examination Survey(KNHANES). We identify the number of effective blood data of obesity in the final model as 6 ~ 8 factors that differ somewhat depending on age and gender. Also, the coefficient of determination that represents the predictive power of obesity in the regression model is the highest for both men and women of aged 19 and in their 20s and 30s, and the predictive power decreases with increasing age.

• Health Policy and Management
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• v.31 no.2
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• pp.232-239
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• 2021

This study aimed to update suicide-related indicators including suicidal ideation, suicide attempts, and the number of suicidal deaths. Based on up-to-date information, we observed the trends of suicide-related indicators. In this study, five data sources were used to observe the trends of suicide-related indicators: Statistics Korea (1983-2019), Korean National Health and Nutrition Examination (KNHANES, '07-13, '15-19), Korean Community Health Survey (KCHS, '08-09, '13, '17), Korean Wealth Panel Study (KOWEPS, '12-19), and Korea Health Panel Survey (KHP, '10-13, '16-17). The suicide rate, which peaked in 2011, declined until 2017 and then started to rise again from 2018, recording a suicide rate of 26.9 per 100,000 people in 2019. The rate of suicidal ideation estimated based on the recently available data was 4.62% (KNHANES, '19), 3.51% (KHP, '16), 2.87% (KHP, '17), and 1.70% (KOWEPS, '19). That of suicide attempt as recent year was 0.43% (KNHANES, '19), 0.07% (KOWEPS, '19). Annual percentage change of death by intentional self-harm was -2.11% (Statistics Korea), and that of suicidal ideation was -14.7% (KNHANES), -2.5% (KCHS), -10.6% (KOWEPS), and -11.3% (KHP). Annual percentage change of suicide attempt was -5.0% (KNHANES), -4.4% (KCHS), and -11.3% (KOWEPS). The lower the income level, the higher the probability of experiencing suicide ideation and suicide attempts. Considering the recent increase in suicide rate in contrast to the continuing decline in suicidal ideation and suicide attempts, continuous data observation and appropriate policies regarding suicide prevention are needed.

• Journal of Preventive Medicine and Public Health
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• v.46 no.2
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• pp.96-104
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• 2013

Objectives: The inherent nature of the Korean National Health and Nutrition Examination Survey (KNHANES) design requires special analysis by incorporating sample weights, stratification, and clustering not used in ordinary statistical procedures. Methods: This study investigated the proportion of research papers that have used an appropriate statistical methodology out of the research papers analyzing the KNHANES cited in the PubMed online system from 2007 to 2012. We also compared differences in mean and regression estimates between the ordinary statistical data analyses without sampling weight and design-based data analyses using the KNHANES 2008 to 2010. Results: Of the 247 research articles cited in PubMed, only 19.8% of all articles used survey design analysis, compared with 80.2% of articles that used ordinary statistical analysis, treating KNHANES data as if it were collected using a simple random sampling method. Means and standard errors differed between the ordinary statistical data analyses and design-based analyses, and the standard errors in the design-based analyses tended to be larger than those in the ordinary statistical data analyses. Conclusions: Ignoring complex survey design can result in biased estimates and overstated significance levels. Sample weights, stratification, and clustering of the design must be incorporated into analyses to ensure the development of appropriate estimates and standard errors of these estimates.

• Journal of muscle and joint health
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• v.28 no.2
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• pp.91-101
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• 2021

Purpose: This study was conducted to identify factors related to osteoporosis prevalence in postmenopausal women. Methods: This study was a secondary analysis research using data from the Eighth Korea National Health and Nutrition Examination Survey (KNHANES VIII-1), 2019, which were downloaded from the KNHANES website. The subjects of this study were 1,791 postmenopausal women who participated in the KNHANES VIII-1, 2019. Data analysis was performed using the IBM SPSS 21.0 program and complex sample design analysis was performed considering factors such as weight, cluster, and strata. Results: Osteoporosis prevalence of in postmenopausal women was 17.5%. Factors related to osteoporosis prevalence were age (65~74 years old, ≥75 years old), house income (low), household type (one-person household), postmenopausal period (10~19 years), drinking (non-drinking). Conclusion: Interventions for osteoporosis prevention and management in postmenopausal women need to focus on women less than 10 years after menopause and one-person household women. Furthermore, it is necessary to expand bone density testing for the early detection of osteoporosis in postmenopausal women.

• Health Policy and Management
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• v.27 no.1
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• pp.75-79
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• 2017

Suicide is becoming a public health issue in many countries, and even more so in Korea. Korea has the highest suicide rate in the Organization for Economic Cooperation and Development countries. To address these issues, we investigated the recent trends in suicidal ideation and suicide attempts among the adult population. We used data from four sources: Korean National Health and Nutrition Examination Survey (KNHANES, '2007-2012, '2013, '2015), Korean Community Health Survey (KCHS, '2008-2009, '2013), Korean Wealth Panel Study (KOWEPS, '2012-2015), and Korea Health Panel Survey (KHP, '2010-2013). Weighted frequencies and trend tests were used. The rate of suicidal ideation as recent year was 5.10% (KNHANES, '2015), 8.95% (KCHS, '2013), 2.34% (KOWEPS, '2015), or 5.39% (KHP, '2013). Regarding the suicide attempts, the rate of suicide attempts as recent year was 0.61% (KNHANES, '2015), 0.41% (KCHS, '2013), or 0.04% (KOWEPS, '2015). Average percent change of suicidal ideation during survey year was -2.80% (KNHANES, '2007-2012), 5.78% (KNHANES, '2013-2015), 0.62% (KCHS, '2008-2013), -5.63% (KOWEPS, '2012-2015), and -10.94% (KHP, '2010-2013). Average percent change of suicide attempts during survey year was -3.84% (KNHANES, '2007-2012), 4.55% (KNHANES, '2013-2015), -2.54% (KCHS, '2008-2013), and -18.96% (KOWEPS, '2012-2015). Those who had lower income level were more likely to have self-reported suicidal ideation and suicide attempts. Our results suggest that further efforts are needed for more effective intervention to identify and manage low income strata with suicide problem.

• Health Policy and Management
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• v.29 no.1
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• pp.77-81
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• 2019

Suicide is a major public health issue that causes over 800,000 deaths each year globally. Korea ranks high in suicide rates, in which around 24.3 per 100,000 individuals are reported to have died by intentional self-harm in 2017 according to Statistics Korea. The aim of this study was to examine the current status and trend of suicide ideation and attempt using data from the following five sources: Korean National Health and Nutrition Examination (KNHANES, '07-13, '15-17), Korean Community Health Survey (KCHS, '08-09, '13, '17), Korean Wealth Panel Study (KOWEPS, '12-17), Korea Health Panel Survey (KHP, '10-13), and Statistics Korea (1983-2017). Suicide ideation and attempts were also further examined based on equalized household income levels. Data published by Statistics Korea were used to show the updated suicide rate and number of deaths by intentional self-harm. The rate of suicide ideation at the recent year was 4.73% (KNHANES, '17), 6.96% (KCHS, '17), 1.63% (KOWEPS, '17), and 5.39% (KHP, '13). That of suicide attempts as recent year was 0.71% (KNHANES, '17), 0.32% (KCHS, '17), and 0.09% (KOWEPS, '17). Annual percentage change of suicidal ideation was -15.4% (KNHANES, '07-17), -2.5% (KCHS, '08-17), -8.6% (KOWEPS, '12-17), and -10.9% (KHP, '10-13). Annual percentage change of suicide attempts was -4.0% (KNHANES, '07-17), -4.4% (KCHS, '08-17), and -14.9% (KOWEPS, '12-17). Individuals with lower income levels were more likely to experience suicide ideation and attempts. Considering that Korea still shows a high suicide rate despite the continuously decreasing trend of suicide ideation and attempt, continuous observation and appropriate policy implementation regarding suicide related problems are necessary.

• Health Policy and Management
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• v.32 no.2
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• pp.228-236
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• 2022

The aim of this study was updating suicide-related indicators, including the number of suicidal deaths, suicide rate, and the prevalence of suicidal ideation and suicide attempts. We observed trends in suicide-related indicators based on up-to-date information. This study used five data sources to evaluate the trends of suicide-related indicators: Statistics Korea (1983-2020), Korean Wealth Panel Study (KOWEPS, 2012-2020), and Korea Health Panel Survey (KHP, 2010-2013, 2016-2018), Korean National Health and Nutrition Examination (KNHANES, 2007-2013, 2015-2020), and Korean Community Health Survey (KCHS, 2008-2009, 2013, 2017). The suicide rate per 100,000 population decrease from 26.9 in 2019 to 25.7 in 2020. Based on recently available data, the rates of suicidal ideation were 1.48% (KOWEPS, 2020), 2.61% (KHP, 2018), 4.62% (KNHANES, 2019), and 6.96% (KCHS, 2017). Those of suicide attempt as were 0.07% (KOWEPS, 2020), 0.44% (KNHANES, 2020), and 0.32% (KCHS, 2017). Annual percentage change (APC) of suicide rate was -1.87% (Statistics Korea, 2011-2020). APC of suicidal ideation was -10.7% (KOWEPS, 2012-2020), -11.5% (KHP, 2010-2013, 2016-2018), -14.7% (KNHANES, 2007-2013, 2015, 2017, 2019), and -2.5% (KCHS, 2008-2009, 2013, 2017). APC of suicide attempt was -11.3% (KOWEPS, 2012-2019), -5.2% (KNHANES, 2007-2013, 2015-2020), and -4.4% (KCHS, 2008-2009, 2013, 2017). Although the suicide rate in Korea has decreased compared to 10 years ago, it is still at a high level. Thus, continuous observation and appropriate suicide prevention policies are needed.