Commuting time, working time, and their link to insomnia symptoms among Korean employees: A cross-sectional study.

OBJECTIVE: Although commuting time is an extension of working hours, few studies have examined the relationship between commuting time and insomnia symptoms in relation to working time. Thus, this study investigated the relationship between commuting time and working time and their link to sleep disturbance. METHODS: This study included employees with ≥35 weekly working hours (n = 30,458) using data from the Sixth Korean Working Conditions Survey conducted in Korea between October 2020 and April 2021. The association between commuting time (≤60, 61-120, and >120 minutes) and insomnia symptoms based on working hours (35-40, 41-52, and >52 h/wk) or shift work was investigated using survey-weighted logistic regression analysis. RESULTS: Long commuting time (>120 min/d) combined with >52 working hours/week (OR: 7.88, 95% CI: 2.51-24.71) or combined with 41-52 h/wk (OR: 3.64, 95% CI: 2.15-6.14) was associated with a higher risk of insomnia symptoms compared with the reference group (working hours: 35-40 h/wk; daily commuting time: ≤60 minutes), after controlling for sex, age, socioeconomic factors, and work-related factors. Among shift workers, those with daily commuting time ≤60 minutes (OR: 1.71, 95% CI: 1.39-2.09), 61-120 minutes (OR: 2.63, 95% CI: 1.21-5.74), and >120 minutes (OR: 5.16, 95% CI: 2.14-12.44) had higher odds of insomnia symptoms than nonshift workers with ≤60 minutes daily commuting time. CONCLUSION: Long working hours and shift work are associated with greater risk of insomnia symptoms.

Association between ergonomic risk exposures and insomnia symptoms: a mediation analysis of the 5th Korean working conditions survey.

BACKGROUND: This study investigates the relationship between ergonomic risk exposures and insomnia symptoms, using data representative of Korea's general working population. METHODS: Data from the 5th Korean Working Conditions Survey were used for this study. The eligible population (employees) for the current study was 37,026. Insomnia symptoms were estimated using the minimal insomnia symptom scale (MISS) questionnaire. Logistic regression analysis was conducted to explore the association between ergonomic risks and insomnia symptoms. RESULTS: All the investigated ergonomic risks increased odd ratios (ORs) for insomnia symptoms: Tiring or painful positions (OR, 1.64; 95% CI, 1.43-1.88); lifting or moving heavy loads (OR, 2.33; 95% CI, 1.99-2.71); long periods of standing (OR, 1.47; 95% CI, 1.29-1.69); and repetitive hand or arm movements (OR, 1.46; 95% CI, 1.29-1.67). The mediated proportion of musculoskeletal pain was 7.4% (95% CI, 5.81-10.13), and the mediated proportion of feeling of exhaustion was 17.5% (95% CI, 5.81-10.13). CONCLUSIONS: This study provides evidence for the relationship between ergonomic risks and insomnia symptoms, for which musculoskeletal pains and the feeling of exhaustion may be potential mediators.

Association between social jetlag and self-rated health: Evidence from Korean representative working population.

BACKGROUND: Social jetlag is a circadian misalignment that arises from a discrepancy between activity/sleep schedules on school/work days and free days. This study explored the correlation between social jetlag and self-rated health (SRH) in a representative sample of Korea. METHODS: This study included 8259 working population in the Korea National Health and Nutrition Examination Survey, 2016-2018. Social jetlag was calculated as the difference between the midpoint of sleep time on work day and work-free day. Five-point Likert scale of SRH was used to assess subjective health perception on general health conditions. Multiple logistic regression analysis was performed to calculate the odds ratios (ORs) and 95 % confidence interval (CI) for poor SRH in the 1-2 h or longer than 2 h social jetlag groups compared to that in the reference group (less than 1 h), after adjusting for age, sex, marital status, occupation, household income, and weekly working hours. RESULTS: The proportions of those with <1 h, 1-2 h, >2 h of social jetlag were 63.80 %, 25.67 %, and 10.53 %, respectively. The risk of poor SRH increased as social jetlag increased. Greater social jetlag was significantly associated with an increased likelihood of reporting poor SRH. The adjusted ORs for the groups with social jetlag between 1 and <2 h, and >2 h were 1.100 (95 % CI = 0.935-1.295), and 1.503 (95 % CI = 1.097-1.727), respectively. Moreover, the OR trend was statistically significant (p for trend = 0.008). CONCLUSION: This study found that social jetlag and poor SRH were significantly related in the Korean working population.

Mediation analysis of chronotype, sleep-related factors, and depressive symptoms among workers: a cross-sectional study.

Background: This study aimed to examine the impact of chronotype on depressive symptoms and explore the mediating effects of sleep quality, pre-sleep cognitive arousal, and social jetlag in a sample of wage earners. Methods: A total of 3,917 waged workers were surveyed online in July 2022. Logistic regression and mediation analysis were used to assess the relationship between chronotype (morningness, intermediate, and eveningness) and depressive symptoms (Patient Health Questionnaire ≥ 5), and the mediating effects of Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index (PSQI), and Pre-Sleep Arousal Scale (PSAS). All analyses were adjusted for age, education level, income level, marital status, coffee consumption, alcohol consumption, physical activity, occupation, employment status, and working hours to calculate odds ratios (ORs). Results: The chronotypes of all the participants were divided into morningness (4.7%), intermediate (93.5%), and eveningness (1.8%). Multiple logistic regression analysis showed an increased risk of depression in the eveningness chronotype (OR: 2.96; 95% confidence interval [CI]: 1.51, 5.86). Regarding the mediation analysis, ISI mediated 28.44% (95% CI: 16.39-40.5), PSQI for 31.25% (95% CI: 19.36, 43.15), and PSAS-Cognitive Score (PSAS-C) for 23.58% (95% CI: 10.66, 36.50) of the association between chronotype and depressive symptoms. However, social jetlag did not significantly mediate this relationship. (percentage mediated = 0.75%, 95% CI: -3.88, 5.39). Conclusions: Evening chronotypes exhibit an increased risk of depressive symptoms, which ISI, PSQI, and PSAS-C partially mediated. This suggests that interventions to improve sleep quality and maintain adequate sleep habits may effectively prevent and treat depression in employees with an eveningness chronotype.

Feasibility of using red cell distribution width for prediction of postoperative mortality in severe burn patients: an association with acute kidney injury after surgery.

BACKGROUND: Severe burns cause pathophysiological processes that result in mortality. A laboratory biomarker, red cell distribution width (RDW), is known as a predictor of mortality in critically-ill patients. We examined the association between RDW and postoperative mortality in severe burn patients. METHODS: We retrospectively analyzed medical data of 731 severely burned patients who underwent surgery under general anesthesia. We evaluated whether preoperative RDW value can predict 3-month mortality after burn surgery using receiver operating characteristic (ROC) curve analysis, logistic regression, and Cox proportional-hazards regression analysis. Mortality was also analyzed according to preoperative RDW values and incidence of postoperative acute kidney injury (AKI). RESULTS: The 3-month mortality rate after burn surgery was 27.1% (198/731). The area under the ROC curve of preoperative RDW to predict mortality after burn surgery was 0.701 (95% confidence interval [CI], 0.667-0.734; P < 0.001) with a cut-off point of 12.9. The adjusted hazard ratio in patients with RDW > 12.9 was 1.238 (95% CI, 1.138-1.347; P < 0.001). Subgroup analysis showed that the survival rate was 88.8% for the non-AKI group with RDW ≤ 12.9 and 17.6% for the AKI group with RDW > 12.9. Preoperative RDW was considered an independent risk factor for mortality (odds ratio, 1.679; 95% CI, 1.378- 2.046; P < 0.001). CONCLUSIONS: Preoperative RDW may predict 3-month postoperative mortality in patients with severe burns, while preoperative RDW > 12.9 and postoperative AKI may further increase mortality after burn surgery.

The physical activity paradox in relation to work ability and health-related productivity loss in Korea.

OBJECTIVES: The physical activity paradox suggests that occupational physical activity (OPA), unlike leisure-time physical activity (LTPA), may detrimentally impact health. We explored the relationships of OPA and LTPA with work ability (WA) and health-related productivity loss (HRPL). METHODS: This study included 5,501 workers in Korea who were recruited in 2021 through a web-based cross-sectional questionnaire. The questionnaire was utilized to quantify OPA and LTPA in metabolic equivalents, while WA and HRPL were also measured. Non-parametric regression, using a generalized additive model (GAM), was employed to visualize the relationships of LTPA and OPA with WA and HRPL. Mean differences in WA and HRPL, in relation to OPA and LTPA, were examined using linear regression models. These models were adjusted for covariates including sex, age, body mass index, education level, alcohol consumption, smoking history, insomnia, occupation, hours worked, and income. RESULTS: The GAM and linear regression analyses revealed that higher LTPA corresponded with higher WA and lower HRPL. In contrast, as OPA increased, WA decreased and HRPL increased. However, within the group with high OPA, HRPL was not significantly lower in the high-LTPA subgroup relative to the low-LTPA subgroup (mean difference=1.92%, p=0.343). This pattern was especially pronounced among workers aged 60 years and older, with an increase in HRPL observed with increasing LTPA among the respondents with high OPA. CONCLUSIONS: High LTPA levels were associated with elevated WA and diminished HRPL. In contrast, higher levels of OPA were associated with lower WA and higher HRPL.

Association between discrimination in the workplace and insomnia symptoms.

Background: In Korea, little research has focused on the relationship between discrimination in the workplace and sleep health. Thus, this study aims to investigate the association between such discriminatory experiences and insomnia, a common sleep disorder, using Korean employees' data. Methods: This study used data from the 6th Korea Working Conditions Survey. Discrimination experiences due to age, ethnic background, nationality, race, sex, religion, disability, sexual orientation, educational level, hometown, and employment status were investigated. The Minimal Insomnia Symptom Scale estimated insomnia symptoms. The association between discrimination experience and insomnia symptoms were analyzed using survey-weighted logistic regression analysis. Results: Based on experiences of discrimination over the past 12 months, insomnia symptoms were associated with discrimination experience due to religion (odds ratio [OR]: 3.70; 95% confidential interval [CI]: 1.58-8.69), sex (OR: 2.51; 95% CI: 1.87-3.37), age (OR: 2.30; 95% CI: 1.88-2.81), hometown (OR: 2.07; 95% CI: 1.44-2.97), employment status (OR: 1.69; 95% CI: 1.37-2.10), and educational level (OR: 1.67; 95% CI: 1.31-2.14). Furthermore, the prevalence of insomnia symptoms increased with the number of discrimination experiences. Conclusions: In this study, discrimination experiences due to religion, sex, age, hometown, employment status, and educational level were significantly associated with insomnia symptoms. Furthermore, as the number of discrimination experiences increased, so did the prevalence of insomnia. Preventing workplace discrimination may improve workers' sleep health.

Association between social jetlag and chronic kidney disease among the Korean working population.

Social jetlag refers to the discrepancy between social time and the body's internal rhythm, which can lead to unfavorable health outcomes. However, no study has directly explored the relation between social jetlag and chronic kidney disease (CKD). This study aims to investigate the relationship between social jetlag and CKD in a representative population of South Korea. This study included 8259 currently economically active Korean population in the Korea National Health and Nutrition Examination Survey. Social jetlag was calculated as the difference between the midpoint of sleep time on weekdays and free days. The estimated glomerular filtration rate (eGFR) was calculated the by using the serum creatinine value according to the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Participants with an eGFR less than 60 ml/min/1.73 m2 were defined as CKD cases. The estimated glomerular filtration rate decreased as social jetlag increased. Multiple logistic regression analysis showed that the adjusted odds ratio (95% confidence interval) of CKD for 1-2 h of social jetlag was 0.926 (0.660-1.299), while the odds ratio for more than 2 h was 2.042 (1.328-3.139) when less than 1 h was used as reference. This study found that social jetlag and risk of CKD were significantly related in the Korean working population.

Social jetlag and risk of depression: Results from the Korea National Health and Nutrition Examination Survey.

BACKGROUND: Social jetlag, which is the mismatch between endogenous rhythm and social timing, is prevalent among the working population. Social jetlag may result in mood changes; however, evidence of relationship between social jetlag and depressive disorders has not been fully verified. Hence, this study aimed to investigate the association between social jetlag and depressive symptoms in a representative working population of South Korea. METHODS: This study included 5447 Korean employees in the Korea National Health and Nutrition Examination Survey. Social jetlag was calculated as the difference between the midpoint of sleep time on weekdays and free days. Depressive symptoms were assessed using Patient Health Questionnaire-9. Multiple logistic regression was used to estimate the odds ratio after adjusting for confounding factors. Moreover, social jetlag and continuous depression scores were evaluated using linear regression and generalized additive models. RESULTS: The proportion of the participants who had >2 h of social jetlag was 10.26 %. Depressive symptoms increased as social jetlag increased. Multiple logistic regression analysis showed that the adjusted OR (95 % confidence interval) for 1 to 2 h of social jetlag was 1.355 (0.891-2.059) and for >2 h was 1.859 (1.084-3.187), which <1 h was reference. LIMITATIONS: This study used a cross-sectional design and measurements were based on self-reported scales. CONCLUSION: This study found that social jetlag and depressive symptoms were significantly related in the Korean working population.

Comparison of Adjuvant Hypertonic Saline and Normal Saline for Epidural Block in Patients with Postherpetic Neuralgia: A Double-Blind, Randomized Trial.

Background: In patients with postherpetic neuralgia (PHN), the effectiveness of epidural block and the benefits of adjuvant hypertonic saline (HS) have not been fully determined. Therefore, we investigated these issues in this study. Methods: At a tertiary medical center's single pain clinic in Seoul, Republic of Korea, patients complaining of PHN even after 4 months of herpes zoster onset were enrolled and randomly assigned to either the HS or normal saline (NS) group. After epidural block with adjuvant HS or NS administration according to each protocol, outcomes were assessed at baseline and one and three months after the intervention. The primary outcome was pain intensity on the numerical rating scale (NRS). The secondary outcomes were the insomnia severity index (ISI), the medication quantification scale (MQS), and the global perceived effect of satisfaction (GPES). Results: Thirty-six patients (NS: 17, HS: 19) were included in the intention-to-treat analysis. The estimated pain intensity decreased in both groups at one and three months after the procedure (P < 0.001), without a significant group difference. The estimated ISI and MQS were not significantly different at 1 month compared with baseline but significantly decreased at 3 months in each group (P < 0.001 and P < 0.001, respectively), without group differences. In addition, there was no difference between the groups on the GPES scale at one and three months after the procedure. Conclusions: Epidural steroid injection may have the advantages of short-term pain relief, improved sleep quality, and decreased medication usage in patients with PHN. In addition, adjuvant HS administration with epidural steroid injection did not show beneficial effects in patients with PHN. Further studies are needed to clarify the potential effectiveness of HS in treating neuropathic pain such as PHN. This trial is registered with KCT0002845.

Association between occupational exposure to chemical or physical factors and sleep disturbance: An analysis of the fifth Korean Working Conditions Survey.

OBJECTIVE: A range of risk factors in occupational environments can negatively affect the sleep of workers. Although psychosocial factors have been emphasized in various studies, few have reported on the relationship between physical or chemical exposure in the workplace and sleep disturbances. Thus, this study aimed to investigate the relationship between occupational exposure to physical or chemical factors and sleep disturbances. DESIGN: Cross-sectional study. SETTING: Data from the fifth Korean Working Conditions Survey (KWCS). PARTICIPANTS: The target population of the fifth KWCS was economically active individuals aged 15 years or older in all Korean households in 2017, resulting in a total study population of 50,176 participants. After excluding the unemployed, full-time students, homemakers, and the retired, 36,996 employees were included in the current study. MEASUREMENTS: Exposure to occupational physical or chemical risk factors was assessed by multiplying the exposure scales of physical or chemical risk factors and weekly working hours. Sleep disturbance was estimated using the Minimal Insomnia Symptom Scale. RESULTS: In the fully adjusted logistic regression model, exposure to the following risk factors was positively associated with sleep disturbance: vibration (odds ratio [OR], 1.74)); noise (OR, 2.28); high temperatures (OR, 2.43); low temperatures (OR, 2.51); smoke, fume, and dust (OR, 2.12); vapors of solvents or thinners (OR, 3.78); chemical substances (OR, 3.78); and environmental smoking (OR, 5.03). CONCLUSIONS: The results of this study provide evidence of a relationship between occupational exposure to physical or chemical factors and sleep disturbances.

Influence of coexposure to long working hours and ergonomic risk factors on musculoskeletal symptoms: an interaction analysis.

OBJECTIVES: This study explores the interaction between ergonomic risk factors and long working hours on musculoskeletal symptoms by additive and multiplicative scales. DESIGN: We used the data of the fifth Korean Working Condition Survey (KWCS). The KWCS is a cross-sectional study. SETTING: To represent the entire Korean working population, the probability proportion stratified cluster sampling method was used. The face-to-face interview was carried out with a structured questionnaire. MAIN OUTCOMES AND MEASURES: To assess the combined effect of ergonomic risk factors and long working hours on musculoskeletal symptoms, the relative excess risk due to interaction (RERI) and the ratio of ORs were calculated using multiple survey-weighted logistic analysis and postestimation commands. RESULTS: The OR for musculoskeletal symptoms was 1.75 (95% CI 1.28 to 1.39) for exposure to long working hours, 3.49 (95% CI 3.06 to 3.99) for exposure to ergonomic risk factors and 5.07 (95% CI 4.33 to 5.93) for coexposure to long working hours and ergonomic risk factors. The RERI was 0.82 (95% CI 0.11 to 1.53) and the ratio of ORs was 0.83 (95% CI 0.50 to 1.14) CONCLUSION: Our findings suggest that coexposure to both ergonomic risk factors and long working hours has a supra-additive interaction effect on musculoskeletal symptoms. Regulations on working hours and workplace interventions might reduce the musculoskeletal diseases of workers.

The Association Between Organizational Justice and Health-Related Productivity Loss Among Korean Employees.

OBJECTIVES: To investigate the association between organizational justice (OJ) and health-related productivity loss (HRPL) among Korean employees. METHODS: From January 6, 2020 to February 18, 2020, data were collected using a web-based questionnaire. This study measured HRPL using the Work Productivity and Activity Impairment Questionnaire: General Health version. Procedural and interactional justice were measured using the Korean organizational justice questionnaire. Generalized linear models were used for estimating productivity loss based on tertiles of OJ levels, while the productivity loss of employees in low OJ categories was used as a reference group. RESULTS: The nonparametric associations between the OJ levels and the overall HRPL level were observed. High levels of OJ significantly reduced HRPL. CONCLUSIONS: Our results support the hypothesis that high OJ is associated with improved labor productivity.

Association between insomnia and absenteeism or presenteeism among Korean employees.

Background: In Korea, few studies clarify insomnia and its association and absenteeism or presenteeism. Therefore, this study aims to examine the association between insomnia and absenteeism/presenteeism using the sixth Korean Working Conditions Survey. Methods: Insomnia was evaluated by the Minimal Insomnia Symptoms Scale (MISS). Absenteeism and presenteeism were assessed by asking if the employee had experienced absence or working despite being ill for the prior 12 months at the point of the survey. Multiple logistic analyses were conducted to explore insomnia and its association with absenteeism and presenteeism. Results: The odds ratios of insomnia for absenteeism and presenteeism were 3.48 (95% confidence interval [CI]: 2.76-4.39) and 3.68 (95% CI: 3.18-4.26) in the fully adjusted model. As the MISS scores increased, absenteeism and presenteeism showed the increasing trend that odd ratios increased accordingly from the first to the fourth quartile. Conclusions: This study observed that insomnia was related to both absenteeism and presenteeism among Korean employees.

Association between sleep disturbance and occupational injury among Korean employees.

BACKGROUND: Occupational injury has been a serious social problem steadily. Sleep disturbance is a risk factor for occupational injury. However, there were few researches studied on the linking between sleep disturbance and occupational injury in general working population of Korea. Therefore, we explored the association between sleep disturbance and occupational injury among Korean workers. METHODS: This study used data from the 5th Korean Working Conditions Survey. Occupational injury was assessed by asking work related injury for 12 months prior to the point of the survey. Sleep disturbance was assessed using the Minimal Insomnia Symptoms Scale (MISS). To analyze the association between sleep disturbance and occupational injury, multiple logistic regression analysis was conducted. RESULTS: The odds ratio (OR) of sleep disturbance group for occupational injury was 2.57 (95% confidence interval [CI]: 1.68-3.93) in the fully adjusted model. For the association between MISS score and occupational injury, it showed increasing trend that ORs increase from the 1st to the 4th quartiles. The OR of 2nd quartile was 1.10 (95% CI: 0.60-2.01), the OR of 3rd quartile was 2.27 (95% CI: 1.53-3.38) and the OR of 4th quartile was 2.80 (95% CI: 1.84-4.26). CONCLUSIONS: Sleep disturbance was associated with occupational injury. In addition, increasing trend was observed between MISS score and occupational injury. These findings imply that developing of intervention programs to manage sleep disturbance and fatigue may be necessary to prevent occupational injury.

Relationship of epidural patient-controlled analgesia with postoperative bleeding after unilateral total knee arthroplasty: a propensity score-matching analysis.

Although epidural patient-controlled analgesia (PCA) to control postoperative pain after total knee arthroplasty (TKA), the relationship of epidural PCA with postoperative bleeding remains controversial. Therefore, we aimed to evaluate the effect of epidural and intravenous PCA on postoperative bleeding in patients undergoing unilateral TKA. Total of 2467 patients who underwent TKA were divided to intravenous PCA (n = 2339) or epidural PCA (n = 128) group. After 1:1 propensity score-matching, 212 patients were analyzed to assess the associations between the perioperative blood loss and epidural PCA between the groups. Mean postoperative blood loss was significantly greater in epidural PCA than in intravenous PCA (900.9 ± 369.1 mL vs. 737.8 ± 410.1 mL; P = 0.007). The incidence of red blood cell (RBC) administration (> 3 units) was significantly higher in epidural PCA than in intravenous PCA (30.2% vs. 16.0%; OR 2.5; 95% CI 1.201-5.205; P = 0.014). Epidural PCA may be strongly related to postoperative bleeding and the incidence of RBC transfusion of more than 3 units after unilateral TKA, as compared to intravenous PCA. Therefore, the use of epidural PCA may be carefully considered for postoperative pain management in TKA.

Smoking may be more harmful to vasospastic angina patients who take antiplatelet agents due to the interaction: Results of Korean prospective multi-center cohort.

BACKGROUND: The interaction between smoking and the use of antiplatelet agents on the prognosis of vasospastic angina (VA) is rarely investigated. METHODS: VA-Korea is a nation-wide multi-center registry with prospective design (n = 1812). The primary endpoint was the composite occurrence of acute coronary syndrome (ACS), symptomatic arrhythmia, and cardiac death. Log-rank test and Cox proportional hazard model were for statistical analysis. Also, we conducted interaction analysis in both additive and multiplicative scales between smoking and antiplatelet agents among VA patients. For additive scale interaction, relative excess risk due to interaction (RERI) was calculated and for multiplicative scale interaction, the ratio of hazard ratio (HR) was calculated. All statistical analysis conducted by Stata Ver 16.1. RESULTS: Patients who were smoking and using antiplatelet agents had the highest incidence rate in the primary composite outcome. The incidence rate was 3.49 per 1,000 person-month (95% CI: 2.30-5.30, log-rank test for primary outcome p = 0.017) and HR of smoking and using antiplatelet agents was 1.66 (95%CI: 0.98-2.81). The adjusted RERI of smoking and using antiplatelet agents was 1.10 (p = 0.009), and the adjusted ratio of HR of smoking and using antiplatelet agents was 3.32 (p = 0.019). The current study observed the interaction between smoking and using antiplatelet agents in both additive and multiplicative scales. CONCLUSIONS: Smoking was associated with higher rates of unfavorable clinical outcomes among VA patients taking antiplatelet agents. This suggested that VA patients, especially those using antiplatelet agents should quit smoking.

Admission serum potassium levels and prognosis of vasospastic angina.

Hypokalemia is a common electrolyte disturbance and is related to poor prognosis in patients with cardiovascular disease. However, the role of hypokalemia in patients with vasospastic angina (VSA) has not yet been studied. The present study enrolled 1454 patients diagnosed with VSA according to ergonovine provocation test results and available admission serum potassium data. The primary outcome was a composite of cardiac death, acute coronary syndrome, and new-onset life-threatening arrhythmia. Based on a hypokalemia definition as serum potassium concentration ≤ 3.5 mEq/L, the hypokalaemia group included 70 patients (4.8%). The median potassium levels were 3.4 mEq/L [interquartile range (IQR) 3.3-3.5] in the hypokalemia group and 4.1 mEq/L (IQR 3.9-4.3) in the no-hypokalemia group. The median follow-up duration was 764 days. Primary outcomes occurred in seven patients (10.0%) in the hypokalemia group and 51 patients (3.7%) in the no-hypokalemia group. The Kaplan-Meier analysis showed a higher cumulative incidence of primary outcomes in the hypokalemia group compared to that in the no-hypokalemia group (log-rank P = 0.014). Multivariate Cox regression analysis also showed that hypokalemia was an independent predictor of primary outcomes. In conclusion, hypokalemia at admission was associated with adverse clinical outcomes in VSA.

Comparison of calcium-channel blockers for long-term clinical outcomes in patients with vasospastic angina.

BACKGROUND/AIMS: Calcium channel blockers (CCBs) are the most widely prescribed medication for patients with vasospastic angina (VA). However, few studies have compared the prognosis of VA patients who are prescribed different CCBs. METHODS: We enrolled 2,960 patients who received provocation test prospectively in 11 university hospitals in Korea. We divided 1,586 patients received four major CCBs into two groups: a first generation CCB (diltiazem and nifedipine) group and a second generation CCB (amlodipine and benidipine) group. Primary outcome was time to events of composite of death from any cause, acute coronary syndrome (ACS) and symptomatic arrhythmia during 3-year follow-up. We also compared the effect of each CCB on the control of angina symptoms. RESULTS: There was no difference of the primary outcome among the two groups with a cumulative incidence rate of 5.4%, 2.9%, and a person-month incidence rate of 2.33 and 1.26, respectively (hazard ratio [HR], 0.54; 95% confidence interval [CI], 0.25 to 1.17; p = 0.120, as reference with the 1st generation CCBs). The incidence of ACS was significantly lower in 2nd generation CCBs group with a person-month incidence rate of 1.66 vs. 0.35 (HR, 0.22; 95% CI, 0.05 to 0.89; p = 0.034). Use of benidipine showed a significant better control of angina symptom compared with diltiazem for 3 years (odds ratio, 0.17; 95% CI, 0.09 to 0.32; p < 0.0001 at 3rd year). CONCLUSION: The first and second generation CCB groups did not differ in terms of composite outcome occurrence. However, the ACS incidence rate was significantly lower in the users of the 2nd generation CCBs.

The Association between Shift Work and Health-Related Productivity Loss due to Either Sickness Absence or Reduced Performance at Work: A Cross-Sectional Study of Korea.

Background: The purpose of the present study was to investigate the association between shift work and health-related productivity loss (HRPL) due to either sickness absence or reduced performance at work. Methods: From January 2020 to February 2020, data were collected using the web-based questionnaire. Workers in Korea (n = 4197) were selected with the convenience sampling method. To evaluate HRPL, the Korean version of the "Work Productivity and Activity Impairment Questionnaire" was used. The nonparametric association between shift work and HRPL was determined. To estimate productivity loss by shift work, generalised linear models were used, and the productivity loss of workers who did not do shift work was used as the reference. Contrasts between the reference (non-shift work) and shift work, including the shift work subtype, were demonstrated. In the adjusted model, age, gender, and occupation were included as covariates. To test whether there were differences in this association by gender, a gender-stratified analysis was conducted. Results: Shift work significantly reduced productivity (2.5% points; 95% CI: 0.2-4.6). The fixed night shift had the largest productivity loss (7.7% points; 95% CI: 1.8-13.7), and the relationship between HRPL and shift work was more prominent among female workers. Conclusions: Shift work is related to an increase in HRPL, and there are gender differences in this association. Our study further indicated that a fixed night shift is most detrimental to workers' health and productivity.