Effect of night shift work on the reduction of glomerular filtration rate using data from Korea Medical Institute (2016-2020).

Background: Shift work increases the risk of chronic diseases, including metabolic diseases. However, studies on the relationship between shift work and renal function are limited. The aim of this study was to investigate the association between shift work and a decreased glomerular filtration rate (GFR). Methods: Data were evaluated for 1,324,930 workers who visited the Korean Medical Institute from January 1, 2016 to December 31, 2020 and underwent a health checkup. Daytime workers were randomly extracted at a ratio of 1:4 after matching for age and sex. In total, 18,190 workers aged over 40 years were included in the analyses; these included 3,638 shift workers and 14,552 daytime workers. Participants were categorized into the shift work group when they underwent a specific health checkup for night shift work or indicated that they were shift workers in the questionnaire. The odds ratio was calculated using a conditional logistic regression to investigate the relevance of shift work for changes in GFR. Results: 35 workers in the shift group and 54 in the daytime group exhibited an estimated GFR (eGFR) value of < 60 mL/min/1.73m2 (p < 0.01). The difference in eGFR values between two checkups differed significantly depending on the type of work (p < 0.01); the difference in the shift work group (-9.64 mL/min/1.73 m2) was larger than that in the daytime work group (-7.45 mL/min/1.73 m2). The odds ratio for eGFR reduction to < 60 mL/min/1.73 m2 in the shift group versus the daytime group was 4.07 (95% confidence interval: 2.54-6.52), which was statistically significant. Conclusions: The results of this study suggest that eGFR decreases by a significantly larger value in shift workers than in daytime workers; thus, shift work could be a contributing factor for chronic kidney disease (CKD). Further prospective studies are necessary to validate this finding and identify measures to prevent CKD in shift workers.

Reliability of the TT-TG Index Versus TT-TG Distance on MRI: Morphometric Analyses in Asian Children and Adolescents.

Background: The tibial tuberosity-trochlear groove (TT-TG) distance measured on magnetic resonance imaging (MRI) is commonly used to decide the treatment for patellar instability; however, the patient's joint size is not considered in this measurement. The TT-TG index has been proposed as a knee size-adjusted measurement for tibial tuberosity location. Purpose: To evaluate the reliability of the TT-TG index compared with the TT-TG distance by analyzing variations in measurement according to age and sex in a pediatric Asian population. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: A total of 698 knee MRI scans were collected in patients between 4 and 18 years of age who did not have any patellofemoral problems. Patient age, sex, height, and weight were recorded. The scans were divided into 5 groups according to patient age (4-6 years, 46 scans; 7-9 years, 56 scans; 10-12 years, 122 scans; 13-15 years, 185 scans; and 16-18 years, 289 scans); MRI scans were also divided by sex (497 male, 201 female). Three independent observers measured the TT-TG distance and TT-TG index on each scan, and age- and sex-based differences in the measurements were evaluated after adjusting for body mass index (BMI). The reliability of the measurements was calculated with the intraclass correlation coefficient (ICC). Results: Good to excellent inter- and intraobserver agreement was found for TT-TG distance (ICC, 0.74) and TT-TG index (ICC, 0.88). The TT-TG distance was significantly different among the groups and increased with age, while variations in the TT-TG index were minimal between age groups and sexes. This finding was also consistent after compensating for the effect of BMI. Conclusion: The TT-TG distance changed with age, while the TT-TG index was relatively constant. Therefore, the TT-TG index may be more reliable and effective for diagnosing and planning treatment, especially in children and adolescents.

Instructor factors associated with medical students' lecture evaluation: a longitudinal analysis.

PURPOSE: This study identified factors that affect lecture evaluation by analyzing sophomores from Dankook University, examining each cluster's characteristics, and comparing differences among trajectories. METHODS: This study identified factors that affect lecture evaluation by analyzing sophomores from Dankook University, examining each cluster's characteristics, and comparing differences among trajectories. RESULTS: The lecture evaluation score decreased as the teaching hours per instructor in a year increased by an hour, and the number of instructors per lecture increased by one individual. During trajectory analysis, the first trajectory had lower lecture evaluation scores overall but relatively high appropriateness of the textbook and punctuality of class, whereas the second trajectory had higher lecture evaluation scores overall for all four items. CONCLUSION: The two trajectories showed differences in teaching methods (understanding of lecture content and usefulness of the lecture) rather than in external factors (appropriateness of the textbook and punctuality of class). Therefore, to improve lecture satisfaction, enhancing instructors' instructional competencies through lectures and adjusting the teaching hours by assigning an adequate number of instructors per lecture are recommended.

Impact of Long Working Hours and Shift Work on Unmet Health Care Need Among Korean Workers.

Background: This study aimed to identify work-related risk factors, including long working hours and night/shift work, for unmet health care need using data of a representative panel of Korean adults. Methods: Associations between work-related factors and unmet health care need were analyzed using data of 3,440 participants (10,320 observations) from the 2011-2013 Korean Health Panel Study. A generalized estimating equation was used for the analysis of repeated measures. Results: The prevalence of unmet health care was 16.6%. After adjusting sex, age, socioeconomic status, work characteristics, and working more than 60 hours per week (odds ratio [OR]: 1.43, 95% confidence interval [CI]: 1.23-1.65) or 50-59 hours per week (OR: 1.26, 95% CI: 1.08-1.46) instead of 40-49 hours per week and night/shift work (OR: 1.27, 95% CI: 1.06-1.51) were associated with unmet health care need. Conclusion: Long working hours and night/shift work are risk factors for unmet health care need among the Korean working population.

The relevant factors of work-related fatigue for occupational vibration-exposed employees.

Background: To date, little is known about the effects of factors linked to work-related fatigue on vibration-exposed workers. Thus, the purpose of this study was (1) to assess the effects of vibration exposure time per week and work-related fatigue on workers and (2) to identify factors associated with work-related fatigue caused by long-term exposure to occupational vibration. Methods: This study used data collected from the 5th Korean Working Conditions Survey. A total of 34,820 non-vibration-exposed and 10,776 vibration-exposed employees were selected from the data. The χ2 and multiple logistic regression were used to determine the effect of vibration exposure time per week and the effects of factors of work-related fatigue on workers. Results: The prevalence of work-related fatigue in vibration-exposed workers (30.5%) was higher than that of non-exposed workers (15.9%). The prevalence of work-related fatigue was higher for female and workers with depression, anxiety, and shift work, and those with authority to control their work pace had statistically significantly higher odds than those who did not. The employees who had the authority to control their order of work (odds ratio [OR]: 0.88; 95% confidence interval [CI]: 0.81-0.95) and method of work (OR: 0.90; 95% CI: 0.82-0.98) had statistically significantly lower odds than those who did not. The OR of work-related fatigue symptoms was highest among employees whose vibration exposure time per week were 30.0%-40.0% (OR: 2.36; 95% CI: 1.96-2.83). Lower OR was observed as vibration exposure time per week decreased. Conclusions: The results of the present study suggest an association between occupational vibration and work-related fatigue and longer vibration exposure time per week, causing an increased prevalence of work-related fatigue symptoms. Measures to protect workers exposed to occupational vibration from work-related fatigue must be taken.

Maternal working hours and smoking and drinking in adolescent children: based on the Korean National Health and Nutrition Examination Survey VI and VII.

BACKGROUND: Adolescent smoking and drinking are influenced by parental supervision. This study aimed to investigate the gap in adolescent smoking and drinking experience rates and age at initiation according to maternal working hours. METHODS: Data from 1,580 adolescents aged 12-18 years and 1,172 working mothers of double-parent or single-mother households were selected from the Korean National Health and Nutrition Examination Survey (KNHANES) VI & VII data. Figures on adolescents' smoking and drinking rates and their ages at imitation were used. Maternal working hours were divided into < 40 hours, 40-52 hours, and > 52 hours to analyze whether smoking and drinking experience rates and age at initiation differ according to maternal working hours and by the child's sex. Maternal age, education level, household income, occupation, shift work, current smoking status, monthly drinking frequency and child's obesity, stress recognition and depressive mood were adjusted for in the statistical analyses. RESULTS: The odds for adolescents' smoking behavior were significantly higher with increasing maternal working hours in boys but not in girls. The odds for adolescents' drinking behavior were not significantly higher in both boys and girls. Regardless of the child's sex, there were no significant differences in the age of smoking and drinking initiation according to maternal working hours. CONCLUSIONS: Adolescents of mothers who work long hours are at a higher risk of being exposed to smoking. Thus, our society needs to share the burden of raising children, which is concentrated on women, and employers and governments should support policies that can help prevent long working hours.

The expression of substance P and calcitonin gene-related peptide is associated with the severity of tendon degeneration in lateral epicondylitis.

BACKGROUND: In this study, we investigated whether substance P (SP) or calcitonin gene-related peptide (CGRP) expression is associated with tendon degeneration in patients with lateral epicondylitis. METHODS: Twenty-nine patients who underwent surgical treatment for lateral epicondylitis were enrolled in the final analyses. Extensor carpi radialis brevis tendon origins were harvested for histological analysis. RESULTS: SP and CGRP immunostaining were negative in healthy tendons but positive in degenerative tendons; moreover, their immunoreactivity increased with degeneration severity. Univariate analysis indicated that variables such as the preoperative visual analog scale (VAS) score or SP or CGRP expression levels were significantly associated with the Movin score. However, multivariate analysis revealed that only higher SP and/or CGRP signals were associated with higher Movin scores. Elevations in SP or CGRP expression were also linked with significantly severe preoperative VAS scores. CONCLUSION: We demonstrated that tendon degeneration severity is associated with increased SP and CGRP expression in the biopsy samples of lateral epicondylitis.

Environmental and Occupation Factors Associated with Vitamin D Deficiency in Korean Adults: The Korea National Health and Nutrition Examination Survey (KNHANES) 2010-2014.

While exposure to sunlight is a well-documented primary source of vitamin D supply, factors leading to vitamin D deficiency vary according to population characteristics. Using nationwide data from the Korea National Health and Nutrition Examination Survey (KNHANES), we aimed to investigate a diverse range of potential factors in association with vitamin D deficiency. Overall, 21,208 participants aged ≥20 years were selected from KNHANES conducted between 2010 and 2014. The associations between various environmental and occupational factors and vitamin D deficiency (defined as serum 25-hydroxyvitamin D [25(OH)D] < 20 ng/mL) were evaluated in logistic regression models after controlling for potential covariates and also after stratification for age and sex. Under given criteria, 15,138 (71.4%) participants were vitamin D deficient. Significant associations were observed between vitamin D deficiency and average environmental temperature and radiation, weekly walking frequency, type of occupation, and shift work. When participants were stratified by age and sex, we observed greater associations of vitamin D deficiency with walking frequency among young males (odds ratio [OR] and 95% confidence interval [95% CI]: 1.24 [1.05-1.47] for those walking <5 times per week compared to those walking ≥5 times per week) and shift work (OR [95% CI]: 1.40 [1.10-1.78] for those working at night compared to those working during the day). We also observed a significant association of vitamin D deficiency with educational attainment (OR [95% CI]: 1.43 [1.09-1.89] for those with ≤middle school compared to those with ≥high school) among older group of females. This study suggests that vitamin D deficiency is related to geographical conditions and subpopulation characteristics. The age and sex-specific associations may urge the effective promotion of vitamin D supply recommendations.

Convolutional-neural-network-based diagnosis of appendicitis via CT scans in patients with acute abdominal pain presenting in the emergency department.

Acute appendicitis is one of the most common causes of abdominal emergencies. We investigated the feasibility of a neural-network-based diagnosis algorithm of appendicitis by using computed tomography (CT) for patients with acute abdominal pain visiting the emergency room (ER). A neural-network-based diagnostic algorithm of appendicitis was developed and validated using CT data from three institutions who visited the ER with abdominal pain and underwent abdominopelvic CT. For input data, 3D isotropic cubes including the appendix were manually extracted and labeled as appendicitis or a normal appendix. A 3D convolutional neural network (CNN) was trained to binary classification on the input. For model development and testing, 8-fold cross validation was conducted for internal validation and an ensemble model was used for external validation. Diagnostic performance was excellent in both the internal and external validation with an accuracy larger than 90%. The CNN-based diagnosis algorithm may be feasible in diagnosing acute appendicitis using the CT data of patients visiting the ER with acute abdominal pain.

MRI features and texture analysis for the early prediction of therapeutic response to neoadjuvant chemoradiotherapy and tumor recurrence of locally advanced rectal cancer.

OBJECTIVES: This study aimed to evaluate the efficiency of imaging features and texture analysis (TA) based on baseline rectal MRI for the early prediction of therapeutic response to neoadjuvant chemoradiotherapy (nCRT) and tumor recurrence in patients with locally advanced rectal cancer (LARC). METHODS: Consecutive patients with LARC who underwent rectal MRI between January 2014 and December 2015 and surgical resection after completing nCRT were retrospectively enrolled. Imaging features were analyzed, and TA parameters were extracted from the tumor volume of interest (VOI) from baseline rectal MRI. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the optimal TA parameter cutoff values to stratify the patients. Logistic and Cox regression analyses were performed to assess the efficacy of each imaging feature and texture parameter in predicting tumor response and disease-free survival. RESULTS: In total, 78 consecutive patients were enrolled. In the logistic regression, good treatment response was associated with lower tumor location (OR = 13.284, p = 0.012), low Conv_Min (OR = 0.300, p = 0.013) and high Conv_Std (OR = 3.174, p = 0.016), Shape_Sphericity (OR = 3.170, p = 0.015), and Shape_Compacity (OR = 2.779, p = 0.032). In the Cox regression, a greater risk of tumor recurrence was related to higher cT stage (HR = 5.374, p = 0.044), pelvic side wall lymph node positivity (HR = 2.721, p = 0.013), and gray-level run length matrix_long-run low gray-level emphasis (HR = 2.268, p = 0.046). CONCLUSIONS: Imaging features and TA based on baseline rectal MRI could be valuable for predicting the treatment response to nCRT for rectal cancer and tumor recurrence. KEY POINTS: • Imaging features and texture parameters of T2-weighted MR images of rectal cancer can help to predict treatment response and the risk for tumor recurrence. • Tumor location as well as conventional and shape indices of texture features can help to predict treatment response for rectal cancer. • Clinical T stage, positive pelvic side wall lymph nodes, and the high-order texture parameter, GLRLM_LRLGE, can help to predict tumor recurrence for rectal cancer.

Effect of night shift work on the control of hypertension and diabetes in workers taking medication.

BACKGROUND: Night shift work induces physiological and psychological stress by altering sleep and biological rhythms and is associated with hypertension, diabetes, obesity, and cardiovascular diseases. Few studies have been conducted on the control of hypertension and diabetes. This study aimed to examine the effect of night shift work on the control rate of hypertension and diabetes. METHODS: Subjects comprised workers aged 20-65 years who underwent specific health examination at a single facility in seven different affiliated examination centers from 1 January to 31 December 2016. Workers were categorised into day workers and night shift workers. Demographic and medical history were taken, and physical examination was done. Blood pressure (BP) and fasting glucose were measured. The control rate of each disease was evaluated based on treatment goals presented in the treatment guidelines of the Korean Society of Hypertension and the Korean Diabetes Association (systolic BP < 140 mmHg and diastolic BP < 90 mmHg; fasting glucose ≤ 130 mg/dL). RESULTS: Among 631,418 subjects, 11.2% (70,450) were night shift workers. Of whom 6.1% (4,319) were taking antihypertensive medication and 2.5% (1,775) were taking diabetes medication. Among patients taking antihypertensive medications, the proportion of those whose BP was controlled to suit treatment goals was 81.7% (26,635) of day workers and 77.4% (3,343) of night shift workers, which was significantly different (p < 0.001). Among patients taking diabetes medications, the proportion of those whose blood glucose was controlled to suit treatment goals was 37.4% (4,489) of day workers and 36.5% (647) of night shift workers, but the difference was not significant. The control rates for patients taking antihypertensive medications (odds ratio [OR]: 0.74, 95% confidence interval [CI]: 0.68-0.80) were lower among night shift workers than day workers with adjustment for age, sex, smoking history, alcohol consumption, exercise, and obesity. However, there were no differences in control rates for patients taking diabetes medications (OR: 0.99, 95% CI: 0.87-1.10) between day workers and night shift workers. CONCLUSIONS: Night shift work can have an effect on the uncontrolled BP in workers taking antihypertensive medications. Therefore, additional efforts for disease control are necessary for night shift workers with hypertension.

Association between the return-to-work hierarchy and self-rated health, self-esteem, and self-efficacy.

PURPOSE: This study aimed to examine whether change of employer and/or job upon return-to-work after work-related injuries and diseases is related to health outcomes; self-rated health, self-esteem, and self-efficacy were used as indicators. METHODS: Data from the Panel Study of Workers' Compensation Insurance in Korea were used. A total of 1,610 workers who had returned to work after work-related injuries and diseases were included. The workers were divided into four groups according to their return-to-work characteristics: same employer, same job (n = 660); same employer, different job (n = 57); different employer, same job (n = 318); and different employer, different job (n = 575). Self-rated health, Rosenberg Self-Esteem Scale, and Self-Efficacy Scale scores were used as outcome variables. Logistic regression analysis was used. RESULTS: Compared to workers who had returned to the same employer and same job, those who had returned to the same employer but a different job were less likely to report good self-rated health (odds ratio [OR] 0.54; confidence interval [CI] 0.30-0.97). Those returning to a different employer but the same job were less likely to report good self-rated health (0.47, 0.35-0.64) and high self-esteem (0.73, 0.55-0.96). Those returning to a different employer and different job were less likely to report good self-rated health (0.49, 0.38-0.63), high self-esteem (0.68, 0.54-0.86), and high self-efficacy (0.66, 0.52-0.83). CONCLUSIONS: Change of employer and/or job related to health outcomes. Returning to the same employer and same job should be set as a goal in the vocational rehabilitation process.

The Relationship between Free Press and Under-Reporting of Non-Fatal Occupational Injuries with Data from Representative National Indicators, 2015: Focusing on the Lethality Rate of Occupational Injuries among 39 Countries.

The epidemiology of occupational injuries is reported worldwide, but suspicions of under-reporting prevail, probably associated with free press. We examined the association between freedom of the press and lethality rate of occupational injuries based on the most comprehensive International Labour Organization database on labour statistics (ILOSTAT) among 39 countries. The occupational injury indices, national indicators, and information on freedom of the press in 2015 were sourced from ILOSTAT, World Bank open data, World Health Organization and Freedom House. The lethality rate was the number of fatal occupational injuries per 10,000 total occupational injuries. The relationship among fatal and total occupation injury rates, lethality rate, and national statistics were analysed using Spearman's rank correlation coefficients. Multivariable linear regression models with bootstrap estimation to manage non-normality determined freedom of the press associated with lethality rate. Freedom of the press was significantly correlated with fatal and total occupational injury rate and lethality rate of occupational injuries. Adjusting for national indicators, only freedom of the press was associated with lethality rate per 10,000 occupational injuries in the report of ILOSTAT. The lethality rate of occupational injury reported by each country might not reflect the actual lethality, but under-reported nonfatal occupational injuries, probably relating to freedom of the press.

The relationship between spontaneous abortion and female workers in the semiconductor industry.

BACKGROUND: This study investigated the relationship between job type and the risk for spontaneous abortion to assess the reproductive toxicity of female workers in the semiconductor industry. METHODS: A questionnaire survey was administered to current female workers of two semiconductor manufacturing plants in Korea. We included female workers who became pregnant at least 6 months after the start of their employment with the company. The pregnancy outcomes of 2,242 female workers who experienced 4,037 pregnancies were investigated. Personnel records were used to assign the subjects to one of three groups: fabrication process workers, packaging process workers, and clerical workers. To adjust for within-person correlations between pregnancies, a generalized estimating equation was used. The logistic regression analysis was limited to the first pregnancy after joining the company to satisfy the assumption of independence among pregnancies. Moreover, we stratified the analysis by time period (pregnancy in the years prior to 2008 vs. after 2009) to reflect differences in occupational exposure based on semiconductor production periods. RESULTS: The risk for spontaneous abortion in female semiconductor workers was not significantly higher for fabrication and packaging process workers than for clerical workers. However, when we stratified by time period, the odds ratio for spontaneous abortion was significantly higher for packaging process workers who became pregnant prior to 2008 when compared with clerical workers (odds ratio: 2.21; 95% confidence interval: 1.01-4.81). CONCLUSIONS: When examining the pregnancies of female semiconductor workers that occurred prior to 2008, packaging process workers showed a significantly higher risk for spontaneous abortions than did clerical workers. The two semiconductor production periods in our study (prior to 2008 vs. after 2009) had different automated processes, chemical exposure levels, and working environments. Thus, the conditions prior to 2008 may have increased the risk for spontaneous abortions in packaging process workers in the semiconductor industry.

Dermal and neural toxicity caused by acrylamide exposure in two Korean grouting workers: a case report.

BACKGROUND: Peripheral neuritis caused by acrylamide is well-known, and many Korean grouting workers are frequently exposed to acrylamide in grouting agents that are injected into cracked concrete. We recently encountered two cases of dermal and neural toxicity in Korean grouting workers with exposure to grouting agents that contained a high concentration of acrylamide. CASE PRESENTATION: The first case involved a 44-year-old man with 8 years of waterproofing experience. The patient developed peeling skin on both hands while grouting, which progressed to systemic neurological symptoms, such as reduced sensory function and strength. The patient was diagnosed with peripheral neuropathy caused by acrylamide exposure, and fully recovered after conservative treatment and withdrawal of exposure to the grouting agent. The second case involved a 34-year-old man with 10 years of grouting experience. The patient initially experienced weakness in both legs, which progressed to weakness in his arms and uncontrolled phonation. After being hospitalized, he was diagnosed with cerebellar ataxia and peripheral neuropathy caused by acrylamide exposure, and was discharged after conservative treatment. Our follow-up investigation revealed that both workers were recently exposed to grouting agents that contained higher concentrations of acrylamide, compared to the agents that they had previously been using. CONCLUSIONS: Both workers had workplace acrylamide exposure through dermal contact plus inhalation of dust and vapor, which led to the neural toxicity and dermatitis. Therefore, government studies are needed to investigate the current status of workplace acrylamide use, and to protect workers from the hazardous effects of using acrylamide-containing grouting agents.

The relationship between emotional labor status and workplace violence among toll collectors.

BACKGROUND: This study aimed to identify the emotional labor and workplace violence status among toll collectors by assessing and comparing the same with that in workers in other service occupation. It also aimed to analyze the relationship between emotional labor and workplace violence. METHODS: This study examined emotional labor and workplace violence status in 264 female toll collectors from August 20 to September 4, 2015. The emotional labor was assessed using the Korean Emotional Labor Scale (K-ELS), and a questionnaire was used to examine the presence or absence, and type and frequency of workplace violence experienced by the subjects. A linear regression analysis was also performed to analyze the relationship between workplace violence and emotional labor. RESULTS: The scores on "emotional demanding and regulation (p < 0.001)," "overload and conflict in customer service (p = 0.005)," "emotional disharmony and hurt (p < 0.001)," and "organizational surveillance and monitoring (p < 0.001)" among the sub-categories of emotional labor were significantly high and indicated "at-risk" levels of emotional labor in those who experienced workplace violence, whereas they were "normal" of emotional labor in those who did not. Even after being adjusted in the linear regression analysis, the emotional labor scores for the above 4 sub-categories were still significantly high in those who experienced workplace violence. On comparing the present scores with 13 other service occupations, it was found that toll collectors had the highest level in "emotional disharmony and hurt," "organizational surveillance and monitoring," and "organizational supportive and protective system". CONCLUSIONS: This study found that the toll collectors engaged in a high level of emotional labor. Additionally, there was a significant relationship between emotional labor and the experience of workplace violence among the toll collectors.

The association between subjective socioeconomic status and health inequity in victims of occupational accidents in Korea.

OBJECTIVES: We aimed to investigate the health inequity of victims of occupational accidents through the association between socioeconomic status and unmet healthcare need. METHODS: Data from the first and second Panel Study of Workers' Compensation Insurance were used, which included 1,803 participants. The odds ratio and 95% confidence intervals for the unmet healthcare needs of participants with a lower socioeconomic status and other socioeconomic statuses were investigated using multivariate regression analysis. RESULTS: Among all participants, 103 had unmet healthcare needs, whereas 1,700 did not. After adjusting for sex, age, smoking, alcohol, chronic disease, recuperation duration, accident type, disability, and economic participation, the odds ratio of unmet healthcare needs in participants with a lower socioeconomic status was 2.04 (95% confidence interval 1.32-3.15) compared to participants with other socioeconomic statuses. CONCLUSIONS: The victims of occupational accidents who have a lower socioeconomic status are more likely to have unmet healthcare needs in comparison to those with other socioeconomic statuses.

Physical Activity and Blood Lead Concentration in Korea: Study Using the Korea National Health and Nutrition Examination Survey (2008-2013).

Physical activity normally has a positive influence on health, however it can be detrimental in the presence of air pollution. Lead, a heavy metal with established adverse health effects, is a major air pollutant. We evaluated the correlation between blood lead concentration and physical activity using data collected from the Korea National Health and Nutrition Examination Survey. Multivariate logistic regression analysis was performed after dividing participants according to whether they were in the top 25% in the distribution of blood lead concentration (i.e., ≥ 2.76 µg/dL), with physical activity level as an independent variable and adjusting for factors such as age, sex, drinking, smoking, body mass index, region, and occupation. The high physical activity group had greater odds of having a blood lead concentration higher than 2.76 µg/dL (odds ratio 1.29, 95% CI 1.11-1.51) compared to the low physical activity group. Furthermore, blood lead concentration is correlated with increasing physical activity.

Hospital Qualities Related to Return to Work from Occupational Injury after Controlling for Injury Severity as Well as Occupational Characteristics.

We examined associations between hospital quality in the workers' compensation system and injured patients' return to work after controlling for injury severity, occupational factors, and demographic factors. Return to work data of injured workers were constructed from 2 datasets: 23,392 patients injured in 2009-2011 from the Korea Workers' Compensation & Welfare Service and return to work data from Korea Employment Information Services. After de-identifying the data, quality scores were matched for each hospital that cared for injured patients. Injury severity was measured by Abbreviated Injury Scales. Relative risk and 95% confidence interval were calculated using log binomial regression models. After adjusting for age, sex, injury severity, occupation, factory size, city, and hospital type, the relative risk (95% confidence interval) for the total score was 1.04 (1.02-1.06), 1.06 (1.04-1.09), and 1.07 (1.05-1.10) in the 2(nd), 3(rd), and 4(th) quartiles, respectively, compared to the 1(st) quartile. The RR (95% CI) in the 2(nd), 3(rd), and 4(th) quartiles was 1.05 (1.02-1.07), 1.05 (1.02-1.08), and 1.06 (1.04-1.09) for the process score; and 1.02 (1.01-1.04), 1.05 (1.03-1.07), and 1.06 (1.04-1.09) for the outcome score compared to the 1(st) quartile score, respectively. In conclusion, our study design with blinded merge methods shows that total, process, and outcome qualities are related to the return to work of injured workers after controlling for other factors.

The association between low blood lead levels and the prevalence of prehypertension among nonhypertensive adults in Korea.

OBJECTIVES: Low-level lead exposure has been associated with increases in blood pressure (BP) and impairment of the cardiovascular system. Prehypertension is not categorized as a disease currently; however, individuals with untreated prehypertension are known to be at increased risk of progression to hypertension and mortality caused by cardiovascular disease. We investigated the association between blood lead levels below the threshold for the harmful effects of lead and the prevalence of prehypertension in Korean adults. METHODS: A total of 8,493 participants (3,945 men and 4,548 women) were included in the current analysis, using data from the fourth, fifth, and sixth Korean National Health and Nutrition Examination Survey (KNHANES) in 2007-2013. Blood analysis, self-report questionnaires, and physical examinations were used to assess blood lead levels, BP, and medical history. Odds ratios (OR) and 95% confidence intervals (95% CI) for prehypertension were calculated using multiple logistic regression models. RESULTS: Compared to the first quartile (Q1) blood lead level (0.206-1.539 µg/dl), the ORs (95% CI) were 1.24 (1.04-1.48) in Q2, (1.540-2.056 µg/dl), 1.27 (1.06-1.52) in Q3, (2.057-2.716 µg/dl), and 1.30 (1.07-1.60) in Q4 (2.717-24.532 µg/dl) for the prevalence of prehypertension after adjusting for age, sex, morbidity status, socioeconomic status, and health behavioral variables. CONCLUSIONS: Our large, cross-sectional, nationwide study revealed that blood lead levels below the threshold for the harmful effects of lead were significantly associated with prehypertension. Am. J. Hum. Biol. 28:729-735, 2016. © 2016 Wiley Periodicals, Inc.