Effective service coverage of long-term care among older persons in South Korea.

BACKGROUND: Global population aging, and the accelerated increase in the number of oldest-old adults, over 80 years, has implied a heightened need for long-term care (LTC). We aimed to provide a theoretical care cascade of LTC services to assess publicly funded LTC (Analysis 1) and to investigate the association between the use of LTC insurance (LTCI) and unmet care needs among older people (Analysis 2) in South Korea. METHODS: Analysis 1 used data from the eighth wave (2020) of the Korean Longitudinal Study of Aging (KLoSA), the 2020 National Health Insurance Service LTCI Statistical YearBook and the 2020 National Awareness Survey of LTCI. The care cascade consisted of the target population, service contacts, coverage and outcomes. Analysis 2 used the fifth to eighth waves of KLoSA, and LTCI analysis was based on three groups: not aware, aware but do not use and aware and use. Unmet care needs were defined as the absence of help among older people with care needs. RESULTS: Among 8,489,208 people aged 65 or older in 2020, 1,368,148 (16.1%) were estimated to want care. Of these, 62.7% (N = 857,984) had LTCI service contact and 807,067 (94.1%) of those had used LTCI services in the past year (Analysis 1). Older people who were aware and used LTCI were less likely to report unmet activities of daily living (ADL) (prevalence ratio (PR): 0.34, 95% confidence interval (CI): 0.18-0.66) or unmet instrumental ADL (IADL) needs (PR: 0.27, 95% CI: 0.17-0.43) than those who were not aware (Analysis 2). CONCLUSIONS: This article provides a theoretical cascade to assess LTC provision in South Korea and a preliminary model for other countries. Korea's LTCI is associated with reduced unmet ADL and IADL needs.

Geographic Distribution of Central Nervous System Rehabilitation Treatment in Korea and Its Associated Factors.

BACKGROUND: Health disparity is defined as a difference in the accessibility of medical resources among regions or other factors. In South Korea, there might be a disparity because of the low proportion of public medical institutions. This study aimed to investigate the geographic distribution of rehabilitation treatment and examine the factors associated with the rates of rehabilitation treatment in Korea. METHODS: We used administrative claims data in 2007, 2012, and 2017 from the National Health Insurance Database in Korea. We defined physical therapy and occupational therapy as rehabilitation treatments and analyzed the rate of rehabilitation treatments for administrative districts in 2007, 2012, and 2017. Interdecile range and coefficient of variation were used to investigate the geographic distribution of rehabilitation treatment over time. We applied multiple random intercept negative binomial regression to examine the factors associated with rehabilitation treatment. A total of 28,319,614 inpatient and outpatient claims were submitted for 874 hospitals that provided rehabilitation treatment in 2007, 2012, and 2017. RESULTS: The increase in the mean rates of physical therapy inpatients and outpatients was greater than those for occupational therapy inpatients and outpatients from 2007 to 2017. Both physical therapy and occupational therapy were concentrated in the Seoul Capital Area and other large urban areas. More than 30% of the districts received no rehabilitation treatment. The interdecile range and coefficient of variation for physical therapy declined more than those for occupational therapy from 2007 to 2017. The deprivation index was negatively correlated with physical therapy inpatients, physical therapy outpatients, occupational therapy inpatients, and occupational therapy outpatients. Furthermore, a 1-unit increase in the number of hospital beds per 1,000 people was associated with 1.42 times higher physical therapy inpatient, 1.44 times higher physical therapy outpatient, 2.14 times higher occupational therapy inpatient, and 3.30 times higher occupational therapy outpatient treatment. CONCLUSION: To reduce the geographic inequality in rehabilitation treatment, it is necessary to narrow the gap between the supply and demand of rehabilitation services. Providing incentives or direct provisions from the government might be an alternative.

Self-Formation of Superhydrophobic Surfaces through Interfacial Energy Engineering between Liquids and Particles.

The superhydrophobic surface has been used in ultradry surface applications, such as the maritime industry, windshields, non-sticky surfaces, anti-icing surfaces, self-cleaning surfaces, and so forth. However, one of the main hurdles for the production of superhydrophobic surfaces is high-cost fabrication methods. Here, we report a handy process of self-synthesis fabrication of superhydrophobic surfaces with daily supplies. Driven by the physics of biscuit dunking, we introduce a method to self-synthesize superhydrophobic surfaces from daily supplies by coating a substrate with a liquid (liquids of paraffin from candles or polydimethylsiloxane) and subsequently sprinkling powders (food-desiccant silica, alumina, sugar, salt, or flour). A mechanistic study revealed that the capillary force, governed by surface energy difference, liquid viscosity, and powder pore size, draws the liquid solution into the porous channels within the powders. The entire surface of powders, in turn, is covered with the low-surface-energy liquid to maintain the porosity, creating a 3D porous nanostructure, resulting in a water contact angle over 160°. This work provides a scientific understanding that technological developments are closely related to the science that can be seen in our daily lives. Also, we believe that further intensive studies extended from this work could enable to home-fabricate a superhydrophobic surface, such as a bathtub and sink in bathrooms and a cooking area and sink in kitchens.

Role of SES on the association between childhood parental death and adulthood suicidal ideation: a mediation analysis using longitudinal dataset in South Korea.

BACKGROUND: We sought to examine the association between childhood experience of parental death (CEPD) and adulthood suicidal ideation, and the mediating role of adulthood SES in the association. METHODS: We analyzed a nationally representative dataset of 8609 adults from the Korea Welfare Panel Study, which is a longitudinal cohort dataset in South Korea. CEPD was measured using a question: "During your childhood (0-17 years old), have you experienced the death of parents?" We classified responses of CEPD during 2006-2011 into 'yes,' and the others into 'no.' Suicidal ideation over the past year was assessed annually during 2012-2019. As a potential mediator, adulthood educational attainment and household income in 2011 were included in the analysis. Logistic regression was applied to examine the association of CEPD with adulthood suicidal ideation across age groups (early adulthood, 19-39 years old; middle adulthood, 40-59 years old; late adulthood, ≥60 years old), after excluding people who reported lifetime suicidal ideation in 2011. Causal mediation analysis using a parametric regression model was applied to examine the mediating role of adulthood SES in the association between CEPD and adulthood suicidal ideation. RESULTS: After adjusting for potential confounders including childhood SES, CEPD was significantly associated with adulthood suicidal ideation among the late adulthood group (OR: 1.43; 95% CI: 1.13-1.81), while the association was not statistically significant among the early; and middle adulthood groups. In mediation analysis of adulthood household income, both indirect association (ORNIE: 1.05; 95% CI: 1.02-1.09) and direct association (ORNDE: 1.37; 95% CI: 1.09-1.73) were statistically significant among the late adulthood group. In the mediation analysis of adulthood education attainment among the late adulthood, only a direct association was statistically significant (ORNDE: 1.43; 95% CI: 1.14-1.80). CONCLUSIONS: These results suggest that CEPD could be a risk factor for adulthood suicidal ideation. Furthermore, the findings imply that income security policy might be necessary to reduce suicide among the late adulthood group.

Sexual harassment and its relationship with depressive symptoms: A nationwide study of Korean EMS providers.

BACKGROUND: Emergency medical service (EMS) providers may face sexual harassment (SH) from citizens. No studies have assessed SH prevalence and its association with depressive symptoms among EMS providers in South Korea. METHODS: We conducted a nationwide cross-sectional survey of 1346 EMS providers in South Korea. SH experience was assessed by asking, "During the past 12 months, have you ever experienced sexual harassment on duty by civil citizens?" Depressive symptoms during the preceding week were assessed using the Centers for Epidemiologic Studies Depression Scale. Modified Poisson regression was applied to examine association between SH and depressive symptoms. RESULTS: Among EMS providers, 28.1% of females and 5.6% of males reported sexual harassment. In the gender-stratified analysis, EMS providers those who experienced SH were more likely to have depressive symptoms among females (PR: 2.97, 95% CI: 1.99, 4.44) and males (PR: 2.01, 95% CI: 1.41, 2.86). CONCLUSIONS: Female EMS providers were about five times more likely to experience SH than males.

Association between interpersonal trust, reciprocity, and suicidal behaviors: A longitudinal cohort study in South Korea.

While a growing body of evidence suggest that social capital including interpersonal trust and reciprocity might be associated with mental health outcomes, few studies have explored the relationship with suicidal behaviors. This research examined the prospective association between interpersonal trust and reciprocity and suicidal behaviors using the Korea Welfare Panel Study, a nationally representative longitudinal cohort dataset in South Korea. Interpersonal trust and reciprocity were assessed at the 7th wave of the survey (2012), and each measure was classified into two categories (low vs. high). Experience of suicidal ideation, planning, and attempt was assessed between the 8th (2013) and 10th wave (2015) of the surveys. After adjusting for confounders including lifetime experience of suicidal behaviors at the 7th wave of the survey (2012) as well as socio-demographic information, the low interpersonal trust group was more likely to experience suicidal ideation (OR: 1.30, 95% CI: 1.11-1.53) compared to the high interpersonal trust group whereas no statistically significant association was observed in the reciprocity analysis.

Atomic layer deposition of 1D and 2D nickel nanostructures on graphite.

One-dimensional (1D) nanowires (NWs) and two-dimensional (2D) thin films of Ni were deposited on highly ordered pyrolytic graphite (HOPG) by atomic layer deposition (ALD), using NH3 as a counter reactant. Thermal ALD using NH3 gas forms 1D NWs along step edges, while NH3 plasma enables the deposition of a continuous 2D film over the whole surface. The lateral and vertical growth rates of the Ni NWs are numerically modeled as a function of the number of ALD cycles. Pretreatment with NH3 gas promotes selectivity in deposition by the reduction of oxygenated functionalities on the HOPG surface. On the other hand, NH3 plasma pretreatment generates surface nitrogen species, and results in a morphological change in the basal plane of graphite, leading to active nucleation across the surface during ALD. The effects of surface nitrogen species on the nucleation of ALD Ni were theoretically studied by density functional theory calculations. Our results suggest that the properties of Ni NWs, such as their density and width, and the formation of Ni thin films on carbon surfaces can be controlled by appropriate use of NH3.

Lookism hurts: appearance discrimination and self-rated health in South Korea.

BACKGROUND: Despite a growing body of evidence suggesting that discrimination harms health, the association between appearance discrimination and health has been understudied. Our study investigated the association between perceived appearance discrimination and self-rated health among emerging adults using a nationally representative cohort study in South Korea. METHODS: We analyzed the 2nd-10th (2005-2013) waves of cohort data from the Korean Education Employment Panel (KEEP). KEEP consists of two groups of individuals who were 15 (group I) and 18 (group II) years old at the 1st wave of the survey (2004) and were followed annually. Appearance discrimination was assessed at baseline (19 years old: 5th wave for group I, 2nd wave for group II) and at follow-up (24 years old: 10th wave for group I, 7th wave for group II). Responses of appearance discrimination at the two-time points were classified into four groups: 1) never (no discrimination at both baseline and follow-up); 2) repeated (discrimination at both baseline and follow-up); 3) incident (discrimination only at follow-up); and 4) in error (discrimination only at baseline). Multivariate logistic regression was applied to examine the association between reporting patterns of appearance discrimination and poor self-rated health, adjusting for potential confounders. RESULTS: Compared to those who did not experience appearance discrimination, 'repeated' (OR: 3.70; 95% CI: 2.19-6.27) and 'incident' (OR: 3.10; 95% CI: 1.99-4.83) groups had a higher odds ratio of poor self-rated health after adjusting for potential confounders including respondents' body mass index change and baseline self-rated health. However, no significant association was observed among those who reported appearance discrimination 'in error'. CONCLUSIONS: These results suggest that perceived appearance discrimination is associated with the health of Korean emerging adults considering participants' reporting patterns of appearance discrimination.

People-Oriented Culture and Its Association With Burnout, Depressive Symptoms, and Sleep Problems During COVID-19 Pandemic Among EMS Providers in Korea.

OBJECTIVE: This study examined how perceived people-oriented culture (POC) was associated with burnout, depressive symptoms, and sleep problems during the COVID-19 pandemic among emergency medical service (EMS) providers in Korea. METHODS: We conducted a cross-sectional survey among 693 EMS providers in 2021. RESULTS: Overall, prevalence of personal burnout, work-related burnout, and citizen-related burnout were 61.5%, 60.0%, and 60.6%, respectively. Prevalence of depressive symptoms was 25.1%. Prevalence of poor sleep quality, unrestful sleep, and sleep disturbance were 46.5%, 58.2%, and 52.2%, respectively. Compared to high POC group, higher prevalence of depressive symptoms was observed among medium (prevalence ratio: 1.57, 95% CI: 1.06, 2.32) and low (prevalence ratio: 2.70, 95% CI: 1.92, 3.79) POC group. Similar trends were observed in the analysis of burnout and sleep problems. CONCLUSIONS: Our findings underscore that low POC could play a critical role in worsening burnout, depressive symptoms, and sleep problems among EMS providers.

Customer verbal abuse is associated with depressive symptoms among high-workload cosmetics sales workers in South Korea.

This study sought to investigate whether association between customer verbal abuse and depressive symptoms differed by workload. We conducted a cross-sectional survey of 795 cosmetic sales workers at department store in South Korea. Experience of customer verbal abuse over the past one month was measured by using a yes/no question. Depressive symptoms during the preceding week were assessed by using 20 items from the Center for Epidemiologic Studies-Depression scale. Workload during the past week was measured by asking the number of customers a worker dealt with on average in a day and classified into two categories: 1) Low (15 people or less), and 2) High (more than 15 people). Cosmetics sales workers' experience of customer verbal abuse was associated with a higher prevalence of depressive symptoms (PR: 1.37, 95% CI: 1.15-1.63). After being stratified by workload, customer verbal abuse showed a statistically significant association with depressive symptoms among high workload groups (PR: 1.46, 95% CI: 1.19-1.79), whereas the association was not statistically significant among low workload group (PR: 1.23, 95% CI: 0.91-1.65). Our findings suggest that experience of customer verbal abuse could have a negative influence on depressive symptoms among high-workload cosmetics sales workers in South Korea.

Change in employment status and its causal effect on suicidal ideation and depressive symptoms: A marginal structural model with machine learning algorithms.

OBJECTIVE: This study aimed to assess the causal effect of a change in employment status on suicidal ideation and depressive symptoms by applying marginal structural models (MSM) with machine-learning (ML) algorithms. METHODS: We analyzed data from the 8-15th waves (2013-2020) of the Korean Welfare Panel Study, a nationally representative longitudinal dataset. Our analysis included 13 294 observations from 3621 participants who had standard employment at baseline (2013-2019). Based on employment status at follow-up year (2014-2020), respondents were classified into two groups: (i) maintained standard employment (reference group), (ii) changed to non-standard employment. Suicidal ideation during the past year and depressive symptoms during the past week were assessed through self-report questionnaire. To apply the ML algorithms to the MSM, we conducted eight ML algorithms to build the propensity score indicating a change in employment status. Then, we applied the MSM to examine the causal effect by using inverse probability weights calculated based on the propensity score from ML algorithms. RESULTS: The random forest algorithm performed best among all algorithms, showing the highest area under the curve 0.702, 95% confidence interval (CI) 0.686-0.718. In the MSM with the random forest algorithm, workers who changed from standard to non-standard employment were 2.07 times more likely to report suicidal ideation compared to those who maintained standard employment (95% CI 1.16-3.70). A similar trend was observed in the analysis of depressive symptoms. CONCLUSIONS: This study found that a change in employment status could lead to a higher risk of suicidal ideation and depressive symptoms.

Lack of compensation for COVID-19-related overtime work and its association with burnout among EMS providers in Korea.

OBJECTIVES: This study examined the association between lack of compensation for COVID-19-related overtime work (LCCOW) and burnout among emergency medical service (EMS) providers in Seoul, Korea. METHODS: We conducted a cross-sectional survey of 693 EMS providers in Seoul, Korea. Participants were classified into 3 groups according to their experience of coronavirus disease 2019 (COVID-19)-related overtime work and LCCOW: (1) "did not experience," (2) "experienced and was compensated," and (3) "experienced and was not compensated." Burnout was measured using the Korean version of the Copenhagen Burnout Inventory, which has 3 subdomains: personal burnout (PB), work-related burnout (WRB), and citizen-related burnout (CRB). Multiple linear regression was applied to examine whether LCCOW was associated with burnout after adjusting for potential confounders. RESULTS: In total, 74.2% of participants experienced COVID-19-related overtime work, and 14.6% of those who worked overtime experienced LCCOW. COVID-19-related overtime work showed a statistically non-significant association with burnout. However, the association differed by LCCOW. Compared to the "did not experience" group, the "experienced and was not compensated" group was associated with PB (ß=10.519; 95% confidence interval [CI], 3.455 to 17.584), WRB (ß=10.339; 95% CI, 3.398 to 17.280), and CRB (ß=12.290; 95% CI, 6.900 to 17.680), whereas no association was observed for the "experienced and was compensated" group. Furthermore, an analysis restricted to EMS providers who worked overtime due to COVID-19 showed that LCCOW was associated with PB (ß=7.970; 95% CI, 1.064 to 14.876), WRB (ß=7.276; 95% CI, 0.270 to 14.283), and CRB (ß=10.000; 95% CI, 3.435 to 16.565). CONCLUSIONS: This study suggests that LCCOW could be critical in worsening burnout among EMS providers who worked overtime due to COVID-19.

Selective area atomic layer deposited ZnO nanodot on self-assembled monolayer pattern using a diblock copolymer nano-template.

ZnO nanodots were prepared by selective area atomic layer deposition (SA-ALD) on an octadecyltrichlorosilane (ODTS) self-assembly monolayers (SAMs) patterns formed using a diblock co-polymer (DBC) nanotemplate. In order to transfer well-ordered nanaotemplate in SAMs, SiO2 sacrificial layer was inserted between DBC and SAMs. Cylindrical nanoholes under 16 nm diameters were well-formed on SiO2 layer. SA-ALD of ZnO was successfully performed on by ODTS SAMs.

Health Disparities Among Workers With Standing Position and Limited Restroom Access: A Cosmetics Saleswomen Study in South Korea.

Korean cosmetics sales workers in department stores face harmful working environments, including limited restroom access, working long hours in a standing position, and customer violence. This study investigated health disparities between cosmetics saleswomen and the general population of working women in South Korea. We assessed the prevalence of health indicators, including physician-diagnosed disease, using a cross-sectional survey of 860 Korean cosmetics saleswomen in September 2018. Health indicators of cosmetics saleswomen were compared to those of general working women from the nationally representative datasets (e.g., National Health Insurance Service-National Sample Cohort). We estimated age-standardized prevalence ratios (SPRs) for health outcomes, including physical, mental, and health-related behavioral conditions. Cosmetics saleswomen were more likely to be diagnosed or treated for physical and mental conditions (e.g., cystitis SPR: 4.03, 95% confidence interval [CI]: 3.48-4.65; plantar fasciitis SPR: 23.48, 95% CI: 18.12-29.93; varicose vein SPR: 38.41, 95% CI: 32.18-45.49; and depression SPR: 11.18, 95% CI: 8.53-14.40) compared to general working women. Prevalence of smoking and hazardous alcohol consumption was also higher among cosmetics saleswomen than those of general women workers. Given our findings, further research is needed to identify work-related risk factors that could deteriorate cosmetic sales workers' health in South Korea.

Working Alone, Limited Restroom Accessibility, and Poor Menstrual Health Among Cosmetics Saleswomen in South Korea.

Menstrual hygiene management (MHM) at work has been neglected in occupational health research despite its importance for female workers' health. This study investigated the association between hours of working alone and poor menstrual health among 740 cosmetics saleswomen in South Korea. Hours of working alone in a day were classified into 4 categories. MHM was measured by asking "Over the past six months, have you ever experienced that you could not change your sanitary pad when you need to change it at work?" We also measured the experience of dermatopathy due to unchanged sanitary pads. Cosmetics saleswomen who worked alone for 3 h or more in a day reported a higher prevalence of ever being unable to change the sanitary pads (prevalence ratio [PR] 1.84, 95% confidence interval [CI]: 1.37-2.46) and dermatopathy due to unchanged sanitary pads (PR 2.06, 95% CI: 1.18-3.59) than those who worked alone less than 1 h in a day.

Association Between Intimate Partner Violence and Suicidal Ideation Among Female and Male Adults in South Korea: A Nationally Representative Longitudinal Study.

This study sought to assess the prevalence of intimate partner violence (IPV) victimization and to examine the sex-stratified associations between IPV and suicidal ideation in South Korea. This study used nationally representative longitudinal survey data from 2011 to 2020 of the Korean Welfare Panel Study of 9732 married adults at baseline. Participants were annually asked about IPV experiences of verbal abuse, physical threat, or physical assault over the past year in 2011-2019. Suicidal ideation in the past year was assessed in the following year 2012-2020 of IPV experiences. Using multilevel logistic regression models, we examined the associations between IPV and suicidal ideation among married adults. The prevalence of verbal abuse, physical threat, and physical assault was respectively 19.8%, 3.0%, and 1.4% in females (n = 5056); and 18.8%, 2.7%, and 1.0% in males (n = 4676). After adjusting for potential confounders (e.g., lifetime suicidal ideation and random effects of individuals and households) in the same year when participants had IPV experiences, all types of IPV experiences were statistically associated with suicidal ideation in the following year among both females and males, except for physical threat among males. We found a statistically significant association between physical threat and suicidal ideation among females (adjusted odds ratio: 2.22, 95% confidence interval: 1.62, 3.04), whereas no association was observed among males. Our findings suggest that public health interventions related to suicidal behaviors that can be attributable to experiencing IPV are necessary among both females and males in South Korea.

Adolescent Bullying Victimization at Secondary School and Adult Suicidality and Depressive Symptoms Among 2152 Lesbian, Gay, and Bisexual Adults in South Korea.

This study examined the association between adolescent bullying victimization (ABV) and adult mental health among lesbian, gay, and bisexual (LGB) individuals in South Korea (hereafter Korea). We conducted a cross-sectional survey of 2152 Korean LGB adults in 2016. Based on experiences of and reasons for ABV, participants were categorized into four groups: "never bullied," "bullied due to sexual orientation and gender expression (SOGE)," "bullied due to other reasons," and "bullied, reason unspecified." Compared with participants who have never been bullied during adolescence, those who have been "bullied due to SOGE" were 1.56 times, 1.53 times, and 3.59 times more likely to report depressive symptoms, suicidal ideation, and suicide attempts, respectively. Statistically significant associations with all three mental health indicators were also observed among those who have been "bullied due to other reasons": depressive symptoms (adjusted prevalence ratio [aPR] = 1.72), suicidal ideation (aPR = 1.48), and suicide attempts (aPR = 3.15). This study suggests that ABV may increase depressive symptoms and suicidality in adulthood among LGB individuals.

Health inequalities of 57,541 prisoners in Korea: a comparison with the general population.

OBJECTIVES: This study aimed to examine health disparities between prisoners and the general population in Korea. METHODS: We sought to estimate the prevalence of 17 physical and mental diseases using the nationwide medication prescription dataset among the total population of prisoners (n=57,541) in Korea. Age- and sex- standardized prevalence ratios (SPRs) were estimated to compare the disease prevalence between the prisoners and the general population. The disease prevalence for the general population was calculated from the prescription dataset for a representative of the Korean population (n=926,246) from the 2013 Korean National Health Insurance Service-National Sample Cohort. Furthermore, the prevalence of these diseases was compared between prisoners and a low-income segment of the general population (n=159,781). RESULTS: Compared to the general population, prisoners had higher prevalence of almost all physical and mental diseases, including hyperlipidemia (SPR, 20.18; 95% confidence interval [CI], 19.43 to 20.94), pulmonary tuberculosis (SPR, 9.58; 95% CI, 7.91 to 11.50), diabetes (SPR, 6.13; 95% CI, 5.96 to 6.31), cancer (SPR, 2.36; 95% CI, 2.07 to 2.68), and depression (SPR, 46.73; 95% CI, 44.14 to 49.43). When compared with the low-income population segment, higher prevalence were still found among prisoners for most diseases, including pulmonary tuberculosis (SPR, 6.39; 95% CI, 5.27 to 7.67) and depression (SPR, 34.71; 95% CI, 32.79 to 36.72). CONCLUSIONS: We found that prisoners were more likely to be unhealthy than the general population, even in comparison with a low-income segment of the general population in Korea.

Gender differences in under-reporting hiring discrimination in Korea: a machine learning approach.

OBJECTIVES: This study was conducted to examine gender differences in under-reporting hiring discrimination by building a prediction model for workers who responded "not applicable (NA)" to a question about hiring discrimination despite being eligible to answer. METHODS: Using data from 3,576 wage workers in the seventh wave (2004) of the Korea Labor and Income Panel Study, we trained and tested 9 machine learning algorithms using "yes" or "no" responses regarding the lifetime experience of hiring discrimination. We then applied the best-performing model to estimate the prevalence of experiencing hiring discrimination among those who answered "NA." Under-reporting of hiring discrimination was calculated by comparing the prevalence of hiring discrimination between the "yes" or "no" group and the "NA" group. RESULTS: Based on the predictions from the random forest model, we found that 58.8% of the "NA" group were predicted to have experienced hiring discrimination, while 19.7% of the "yes" or "no" group reported hiring discrimination. Among the "NA" group, the predicted prevalence of hiring discrimination for men and women was 45.3% and 84.8%, respectively. CONCLUSIONS: This study introduces a methodological strategy for epidemiologic studies to address the under-reporting of discrimination by applying machine learning algorithms.

Job insecurity is associated with presenteeism, but not with absenteeism: A study of 19 720 full-time waged workers in South Korea.

OBJECTIVE: This study examined whether perceived job insecurity was associated with absenteeism and presenteeism, and how these associations varied when the differential cutoff was applied to define absenteeism and presenteeism. METHODS: We analyzed a nationally representative dataset of 19 720 full-time waged workers from the 4th Korean Working Conditions Survey (2014). As an independent variable, perceived job insecurity was assessed. As dependent variables, absenteeism and presenteeism were measured. Seven differential cutoffs (from "1 day" to "7 days") were used when defining absenteeism and presenteeism. A Poisson regression model with a robust error variance was applied for the analysis. RESULTS: When "1 day" was cutoff to define absenteeism and presenteeism, job insecurity was not associated with both absenteeism (PR: 1.07, 95% CI: 0.97, 1.16) and presenteeism (PR: 1.05, 95% CI: 1.00, 1.10). When the higher cutoff was used, the association between job insecurity and absenteeism was attenuated and remained statistically nonsignificant. However, statistically significant associations between job insecurity and presenteeism were observed when the differential cutoff was used: "2 days" (PR: 1.07, 95% CI: 1.01, 1.13), "3 days" (PR: 1.14, 95% CI: 1.06, 1.22), "4 days" (PR: 1.15, 95% CI: 1.05, 1.26), "5 days" (PR: 1.18, 95% CI: 1.06, 1.30), "6 days" (PR: 1.17, 95% CI: 1.02, 1.33), and "7 days" (PR: 1.17, 95% CI: 1.02, 1.34). CONCLUSION: This study found that perceived job insecurity was associated with presenteeism, but not absenteeism. Furthermore, the association differed by cutoff applied to define presenteeism among full-time waged workers in South Korea.