Archives of Environmental & Occupational Health
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Job Stress and Mental Health among Nonregular Workers in Korea: What Dimensions of Job Stress are Associated with Mental Health? Soo Kyung Park Ph.D, Min-Kyoung Rhee Ph.D & Michàlle Mor Barak Ph.D To cite this article: Soo Kyung Park Ph.D, Min-Kyoung Rhee Ph.D & Michàlle Mor Barak Ph.D (2014): Job Stress and Mental Health among Nonregular Workers in Korea: What Dimensions of Job Stress are Associated with Mental Health?, Archives of Environmental & Occupational Health, DOI: 10.1080/19338244.2014.997381 To link to this article: http://dx.doi.org/10.1080/19338244.2014.997381
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ACCEPTED MANUSCRIPT Job Stress and Mental Health among Nonregular Workers in Korea: What Dimensions of Job Stress are Associated with Mental Health? Soo Kyung Park, Ph.D; Min-Kyoung Rhee, Ph.D.; Michàlle Mor Barak, Ph.D Acknowledgement: Soo Kyung Park, Ph.D gratefully acknowledges the LG YONAM foundation for its financial support of her sabbatical stay at University of Southern California. This work was supported by the LG YONAM foundation grants in 2011.
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Author Affiliations: Department of Social Welfare, Daejin University, Pocheon-si, South Korea (S.K. Park); School of Social Work, University of Southern California, Los Angeles (M.K. Rhee and M. Mor Barak). Corresponding Author: Min-Kyoung Rhee, School of Social Work, University of Southern California, 669 W. 34th street, Los Angeles, CA 90089-0411 email: [email protected] ABSTRACT Although nonregular workers experience higher job stress, poorer mental health, and different job stress dimensions relative to regular workers, little is known about which job stress dimensions are associated with poor mental health among nonregular workers. This study investigated the association between job stress dimensions and mental health among Korean nonregular workers. Data were collected from 333 nonregular workers in Seoul and Gyeonggi Province and logistic regression analysis was conducted. Results of the study indicated that high job insecurity and lack of rewards had stronger associations with poor mental health than other dimensions of job stress when controlling for sociodemographic and psychosocial variables. It is important for the government and organizations to improve job security and reward systems to reduce job stress among nonregular workers and ultimately alleviate their mental health issues. KEYWORDS: job stress, mental health, nonregular workers, Korea
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ACCEPTED MANUSCRIPT INTRODUCTION According to the U.S. National Institute for Occupational Safety and Health, job stress is defined as “the harmful physical and emotional responses that occur when the requirements of the job do not match the capabilities, resources, or needs of the worker.”1 Approximately 41% to 83% of employees experience job stress,1-4 and rates have increased substantially during the last Downloaded by [Australian National University] at 05:13 08 November 2015
few decades partly due to intensified workloads, high job insecurity, downgraded job quality, and work–family conflict.2,4,5 Although job stress is an important issue for both organizations and employees due to its various adverse consequences,3,6-11 it may be more of a concern for nonregular workers who experience high job insecurity, low wages, and lack of access to social protection and employment benefits.12 In South Korea (hereafter Korea), nonregular workers are defined as individuals who engage in limited-term contract, part-time, or atypical employment including dispatch, subcontract, independent contract, on-call or daily, and tele- or home-based work.13,14 It is estimated that between 33.3% and 47.8% of wage workers are nonregular workers in Korea15,16 marking one of the highest proportions among Organization for Economic Co-operation and Development (OECD) countries.17 Korea’s economic crisis in 1997 and the implementation of neoliberal economic reforms not only substantially increased the number of nonregular workers but also increased wage inequality18 and job insecurity compared to EU15 or OECD countries.19 Korean nonregular workers earned only 57% as much per hour as regular workers in 2010,20 and their average tenure was 2.24 years compared to 8.17 years for regular workers.16 Moreover, they have limited opportunities for promotion, job training, access to social insurance, and other employee benefits such as retirement annuities, bonuses, overtime pay, and paid leave.15,20 These
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ACCEPTED MANUSCRIPT disproportionate employment challenges are likely to create high job stress for nonregular workers, which in turn may negatively affect their mental health or psychological well-being. Previous research has consistently documented empirical evidence of higher job stress and poorer mental health among nonregular workers compared to regular workers.21-26 Research has indicated that nonregular workers experience not only significantly higher job stress than Downloaded by [Australian National University] at 05:13 08 November 2015
regular workers but also different job stress factors.21,22,24 Whereas nonregular workers experience significantly higher job stress due to high job demand, high job insecurity, insufficient job control, lack of rewards, low social support, and lack of fairness or support in the organizational system,21,22,24 regular workers experience job stress due to high job demand and discomfort in occupational climate.22 Discomfort in occupational climate specifically refers to potential stress that can be caused by collective and authoritarian Korean organizational culture, inconsistent job requirements, and gender discrimination. Previous research also has indicated that nonregular workers experienced higher psychological distress such as depression compared to regular workers.23,25,26 Cho and colleagues23 examined job stress and depression among 8,522 workers in 329 workplaces in Korea and found that the prevalence of depression among nonregular workers was significantly higher than that of regular workers. Evidence of the higher prevalence of job stress and mental health problems among nonregular workers suggests the need for more in-depth examination of nonregular workers’ job stress and its relationship with mental health. However, there is a dearth of empirical evidence regarding the relationship between job stress dimensions and mental health specifically related to nonregular workers. Studies that examined differences in job stress dimensions between nonregular and regular workers did not further examine the relationship between job stress and
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ACCEPTED MANUSCRIPT mental health.21,24 In addition, most empirical evidence of the positive relationship between job stress and psychological distress has been related to workers in general.23,26-28 Although Jeon and colleagues22 examined the association between job stress dimensions and psychosocial aspects among 361 hospital workers, their analysis was limited to bivariate examination of correlations. To fill this gap in the literature, this study aimed to estimate the potential effects of Downloaded by [Australian National University] at 05:13 08 November 2015
subdimensions of job stress on mental health by examining which components of job stress were more strongly associated with mental health among nonregular workers in Korea. Two leading theoretical models in job stress research, Karasek’s job demand–control (JDC) model and Siegrist’s effort–reward imbalance (ERI) model, were used as our theoretical framework. The JDC model postulates that high job stress is generated by a combination of high job demands and low job control.29 The ERI model, on the other hand, posits that high job stress is an outcome of a mismatch or lack of reciprocity between high investment of effort (high demands and obligations at work) and low rewards received (lack of promotion opportunities, job insecurity).30 Empirical studies that used these models have indicated that low job control, high demands at work, and effort–reward imbalance are significant factors related to depression and psychosocial distress.31-34 Moreover, low job control and effort–reward imbalance are stronger predictors of mental health problems for employees with high job insecurity.33 Other studies that examined job stress and mental health among Korean employees found that subdimensions of job stress such as job demands, inadequate social support, job insecurity, lack of rewards, and discomfort in occupational climate were associated with higher risk of depression.23,26
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ACCEPTED MANUSCRIPT Based on these two theoretical models of job stress and a review of existing literature, we developed the following hypotheses to estimate the potential effects of subdimensions of job stress on mental health. H1: High job demands are associated with poor mental health. H2: Insufficient job control is associated with poor mental health. Downloaded by [Australian National University] at 05:13 08 November 2015
H3: Inadequate social support is associated with poor mental health. H4: High job insecurity is associated with poor mental health. H5: Low level of fairness or support in the organizational system is associated with poor mental health. H6: Lack of rewards is associated with poor mental health. H7: Discomfort in occupational climate is associated with poor mental health. Based on the aforementioned employment conditions specific to Korean nonregular workers, i.e., high job insecurity, low pay, and less access to social insurance and employment benefits, we also developed the following hypothesis to examine which subscales of job stress are more strongly associated with mental health among nonregular workers in Korea. H8: High job insecurity and lack of rewards are more strongly associated with poor mental health than other dimensions of job stress when controlling for sociodemographic and psychosocial variables. METHODS Study population Study participants were 333 nonregular workers in Seoul and Gyeonggi Province, one of the largest metropolitan areas in Korea. The definition of nonregular workers for this study was
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ACCEPTED MANUSCRIPT based on type of employment and included contingent and part-time workers, dispatched workers indirectly employed through temporary work agencies, temporary help agency workers, independent contractors, on-call and daily workers, and teleworkers and home-based workers. Purposive sampling was employed to recruit participants by sending requests for cooperation to individuals in charge of a university, a district office, a company in the service industry, and three Downloaded by [Australian National University] at 05:13 08 November 2015
apartment buildings to describe the nature of our study and the survey. After receiving permission from these agencies, we visited employees commonly identified as nonregular workers by type of employment, such as cleaning workers, big-box store cashiers, apartment guards, and other contingent and part-time workers. We also confirmed whether or not they were nonregular workers and their willingness to participate. Informed consent was verbally obtained from participants after a full explanation of the purpose of the research and confidentiality issues. Questionnaires were distributed to nonregular workers who had agreed to participate in the selfadministered survey. Participants were assured of the confidentiality and anonymity of their responses. Each participant who answered the questionnaire was given a multiuse coupon (with a value of $5) as a reward. The final analysis relied on information from 333 questionnaires collected in May 2012. This study was approved under the coded data determination by [blinded for review]. Measurement Dependent variable Mental health was assessed using the Hopkins Symptom Checklist (HSCL-25), which is a 25-item version of the Symptom Check List-90. This self-report inventory assesses anxiety (10 items) and depression (15 items) on a 4-point scale (1 = not at all, 2 = a little, 3 = quite a bit, and
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ACCEPTED MANUSCRIPT 4 = extremely). The instrument measures to what extent study participants were bothered by certain symptoms during the past month, including feeling fearful, blaming oneself for things, crying easily, having a poor appetite, and feeling no interest in things, etc. A total score was calculated by averaging all 25 items, with higher scores indicating more psychiatric or affective symptoms. The HSCL-25 scale can be a screening tool for psychiatric problems, with scores Downloaded by [Australian National University] at 05:13 08 November 2015
greater than or equal to 1.75 indicating a probable need for psychiatric treatment.35,36 In this study, we dichotomized mental health using the cutoff point of 1.75 to identify individuals with clinically significant psychiatric problems. Individuals who scored 1.75 or higher in HSCL-25 were classified in a mental health risk group and those who scored less than 1.75 were categorized in a nonrisk group. This measure has been found to be valid in cross-cultural settings,35,37,38 and Cronbach’s alpha of the overall scale in this study was .96. Independent variable Job stress was measured using 24 items of the short form of the Korean Occupational Stress Scale (KOSS-SF), a self-report questionnaire for estimating unique and specific occupational stressors among Korean employees. Chang and his colleagues39 validated the reliability of the KOSS in a nationwide epidemiological study conducted in Korea. The subscales of the KOSS-SF used in this study were job demands (4 items, α = .58), insufficient job control (4 items, α = .78), inadequate social support (3 items, α = .75), job insecurity (2 items, α = .72), organizational system (4 items, α = .79), lack of rewards (3 items, α = .76), and occupational climate (4 items, α = .62). Each item was rated on a Likert scale from 1 (not at all) to 4 (very much). Job stress scores for each subscale were calculated using a formula proposed by Chang et al39: ([obtained score-number of items]/[maximum expected score-number of items] × 100) and
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ACCEPTED MANUSCRIPT adjusted to a scale of 0 to 100. Positive items were reverse coded so that higher scores indicated higher job stress. For further description of subscale items, see Park et al.26 Control variables Control variables include gender, age (≤ 29, 30–39, 40–49, 50–59, ≥ 60), education (middle school or less, high school, college or more), marital status (never married, married or Downloaded by [Australian National University] at 05:13 08 November 2015
partnered, separated/divorced/ widowed), type of nonregular employment (atypical vs. limitedterm contract or part-time), self-perceived economic status (lower/middle-lower class vs. middle/middle-upper/upper class), and self-rated health (very bad/bad vs. similar to others/good/very good). Statistical analyses Pearson’s χ2 tests were used to examine the relationships between general characteristics and mental health. T-tests were used to examine differences in the seven subscales of job stress between the mental health risk group, whose members scored 1.75 or higher on the HSCL-25, and the nonrisk group, whose members scored less than 1.75. Finally, logistic regression was used to estimate associations between job stress and mental health after controlling for sociodemographic and psychosocial variables. Rates of missing data were very low for all measures in the study, and cases with missing data were excluded from the analyses. Data were analyzed using SPSS 12.0 software.
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ACCEPTED MANUSCRIPT RESULTS Descriptive statistics Sociodemographic and psychosocial characteristics of the sample are presented in Table 1; 55.6% of the participants were men and approximately 25% of respondents were in their 40s. A majority of participants had received a high school education or higher, were married, Downloaded by [Australian National University] at 05:13 08 November 2015
perceived themselves as lower class in terms of their economic status, and reported that they had similar or better health compared to others. Regarding employment status, 47.7% were contingent or part-time workers who were directly employed by their employers, whereas 52.3% were dispatched workers who were indirectly employed through temporary work agencies. [Insert Table 1 here] Bivariate analyses We defined the mental health risk group as HSCL-25 ≥ 1.75 and the nonrisk group as HSCL-25 < 1.75. Slightly more than one third of the respondents (35.4%) belonged to the mental health risk group, indicating that they were at significant risk of psychiatric problems and should receive further diagnostic assessment. The results of χ2 tests in Table 1 indicated that there were significant differences between the mental health risk and nonrisk groups with regard to all sociodemographic and psychosocial variables included in the study, except type of nonregular employment. As shown in Table 1, women, those in older age groups, those with a middle school education or less, those who were widowed, separated, or divorced, those who perceived their economic status as lower or middlelower class, and those who rated their health worse compared to others were more likely to have poorer mental health, as evidenced by a significantly higher proportion of HSCL-25 scores above
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ACCEPTED MANUSCRIPT 1.75. No significant associations were found between mental health and type of nonregular employment. [Insert Table 2 here] The mean scores for the seven subscales of job stress by subgroup are presented in Table 2. Mean scores for all subscales of job stress were statistically significantly higher in the mental Downloaded by [Australian National University] at 05:13 08 November 2015
health risk group than the nonrisk group. That is, participants above the HSCL-25 cutoff point perceived that they had more job demands, less job control, less social support, more job insecurity, a less fair organizational system, fewer rewards, and more discomfort in occupational climate. Multivariate Analysis Table 3 presents the results of multivariate analysis examining sociodemographic and psychosocial characteristics and subscales of job stress associated with mental health status. Women had a greater likelihood of being at risk of psychiatric problems than men. Those who received a middle school education or less or a high school education were more likely to be at risk of psychiatric problems than those with a college education or higher. Those who perceived their economic status as low were more likely to score above the HSCL-25 cutoff point than those who did not. Self-rated health was also strongly associated with mental health. Those who rated themselves as less healthy were more likely to score above the HSCL-25 cutoff point than those who assessed themselves as healthy compared to others. Among job stress subscales, job insecurity and lack of rewards had statistically significant relationships with risk of psychiatric problems among nonregular workers. [Insert Table 3 here]
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ACCEPTED MANUSCRIPT DISCUSSION The purpose of this study was to examine which components of job stress were stronger predictors of mental health among nonregular workers in Korea. To achieve this aim, we hypothesized that (1) high job demands, insufficient job control, inadequate social support, high job insecurity, low level of fairness or support in organizational system, lack of rewards, and Downloaded by [Australian National University] at 05:13 08 November 2015
discomfort in occupational climate would be associated with poor mental health and that (2) high job insecurity and lack of rewards would have stronger associations with poor mental health than other dimensions of job stress when controlling for sociodemographic and psychosocial variables. Our analysis showed 35.4% of the study sample belonged to the mental health risk group, scoring 1.75 or higher on the HSCL-25. This indicates that more than one third of respondents were experiencing depression, anxiety, or somatic symptoms that require psychiatric care, a relatively higher proportion than reported in previous research.23,26 Such a high prevalence of mental health problems among nonregular workers may be associated with high job stress caused by job insecurity or low pay. As expected, this study found high job insecurity and lack of rewards to be the only predictors of poor mental health after controlling for covariates, although all seven subscales of job stress were associated with mental health in bivariate analyses. This result can be better understood in the context of the employment conditions of nonregular workers in Korea. As stated in the introduction, high job insecurity, income disparity, lack of opportunities for promotion, and poor access to employment benefits are among the most critical issues for nonregular workers in Korea. Working in highly insecure positions with low pay and limited employment benefits can create high job stress for nonregular workers, which may
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ACCEPTED MANUSCRIPT negatively affect their mental health. Moreover, lack of a social security system and labor market policies to protect nonregular workers may aggravate their job stress and mental health problems. The results of our study are consistent with previous research in the literature. A study by Simmons and Swanberg40 examined the effects of environmental factors, including job type, decision making, work flexibility, support from supervisors and coworkers, and job insecurity, Downloaded by [Australian National University] at 05:13 08 November 2015
on depression levels by economic status. They reported that job insecurity was the only predictor of depression among workers with low economic status. Although depression among those with better economic status was significantly alleviated by support from supervisors and coworkers, those with low economic status and high job insecurity still reported depression after receiving support from supervisors and coworkers and increased work flexibility.40 This indicates that high job insecurity is a significant stressor that harms the mental health of individuals of lower economic status who are mostly nonregular workers. In terms of lack of rewards, the mental health of nonregular workers can be threatened because they typically earn low wages and receive less protection from social insurance despite their economic activity. Because income is not only a representative reward system but also one that provides basic resources to maintain a livelihood, nonregular workers who are economically underprivileged may have particularly high stress that can threaten their mental health. Similar to our results, previous research indicated that a lack of rewards is a significant job stressor for nonregular workers24 and that effort–reward imbalance has a stronger effect on depression among employees with high job insecurity.33 On the other hand, studies that examined specific aspects of job stress that were associated with depression using the KOSS among Korean employees had different results than
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ACCEPTED MANUSCRIPT the present study. According to a study by Cho and colleagues23 of 8,522 Korean employees nationwide, high job demand, insufficient job control, job insecurity, lack of rewards, inadequate social support, and discomfort in occupational climate were significant predictors of depression, and inadequate social support and discomfort in occupational climate were stronger risk factors. However, 81.4% of those surveyed by Cho and his colleagues23 were regular workers and the Downloaded by [Australian National University] at 05:13 08 November 2015
researchers did not distinguish between regular or nonregular workers in their analysis. In addition, because regular workers maintain relatively longer tenure of employment, they may be more exposed to collective Korean organizational culture, such as closely interacting with colleagues and supervisors or dining together with their team members after work. Thus, inadequate social support and discomfort in occupational climate can be significant job stressors for these employees. However, nonregular workers tend to have much shorter tenure than regular workers and may have different values or expectations about relationships with colleagues or supervisors, as well as collective culture. Thus their job stressors may be different than regular workers. Park and colleagues26 examined 3,103 Korean full-time employees in small- and medium-size enterprises and found that job insecurity was the strongest predictor of depression for both men and women, but a lack of rewards was associated with depressive symptoms only for men. These findings, along with ours, confirm that job insecurity is a strong job stressor that adversely affects the mental health of both full-time employees in small- and medium-size enterprises and nonregular workers. In addition, the finding that a lack of rewards was associated with depressive symptoms only for men26 suggests that a lack of rewards can act as a powerful risk factor for depression even for full-time employees when they are economically underprivileged and for men who are often expected to play a role as the main breadwinner.
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ACCEPTED MANUSCRIPT However, this study did not provide specific information on nonregular workers because it included only full-time employees. Our study results also showed that sociodemographic characteristics such as gender and education and psychosocial variables such as self-perceived economic status and self-rated health were associated with a higher prevalence of mental health problems. Women and those Downloaded by [Australian National University] at 05:13 08 November 2015
with lower education levels, lower perceived economic status, and lower self-rated health reported greater risk of adverse mental health problems. These results are supported by previous studies that found women are typically more vulnerable to depression or anxiety,41,42 lower-class workers are more depressed compared to workers in higher economic classes,40 and self-rated health is negatively related to mental health.43 In particular, workers with lower economic status are known to experience high stress when performing work duties because they often have low education levels and poor technical skills coupled with high job insecurity.44 In terms of economic status, it is possible that nonregular workers’ perceptions of their economic status may have played a role in the association between job stress and mental health rather than their actual economic status, because all study participants were nonregular workers who tended to be economically underprivileged. There are several limitations in the current study that need to be considered when interpreting the study results. First, the study employed a cross-sectional design, preventing the assessment of causal relationships among variables. The possibility of reverse causation should be considered. Second, measures of job stress and mental health were based on self-reported data and are subject to self-report bias. For example, Koreans tend to address psychological distress inwardly and have strong stigma against mental illness, and therefore may report less job stress
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ACCEPTED MANUSCRIPT or mental health problems. Third, although we acknowledge that subdimensions of job stress and their relationship with mental health can vary according to certain sociodemographic characteristics such as gender, age, and education because of different work experiences, our analyses did not consider such potential differences due to the limited number of participants in each subgroup. Future studies of job stress and mental health outcomes should consider Downloaded by [Australian National University] at 05:13 08 November 2015
examining whether the association of job stress with mental health is specific to certain sociodemographic characteristics. Fourth, although we focused specifically on nonregular workers based on several rationales, a comparison between nonregular and regular workers, examining how the association of subdimensions of job stress differed by employment type, may have been more informative. This can be addressed in future studies by including a sample of regular workers. In addition, researchers should examine how or whether differences between the two groups change depending on how nonregular workers are defined. Because there is no universal definition of nonregular workers, the composition of regular and nonregular workers can vary, which may affect research results. Despite these limitations, the results of our study provide significant implications for occupational health policy and practice. First, more sophisticated regulations and laws to protect nonregular workers’ rights and quality of employment need to be developed. Because many employers have hired nonregular workers to avoid high labor costs and the difficulty of laying off regular workers, nonregular workers often experience high job insecurity and lack of rewards. Although nonregular employment has become prevalent in Korea, laws and regulations that protect the rights of nonregular workers are relatively weak.45 Second, the coverage of nonregular workers by the social safety net needs to be increased. The social insurance system in
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ACCEPTED MANUSCRIPT Korea was originally designed for regular workers and has limitations in terms of support for nonregular workers. Because most fringe benefits provided by employers depend on their ability to pay for those benefits, nonregular workers and employees at small- and medium-size enterprises, which account for approximately 90% of all workers in Korea, have substantial limitations in terms of receiving work benefits.46,47 Third, diverse interventions need to be Downloaded by [Australian National University] at 05:13 08 November 2015
developed to prevent and manage high job stress among nonregular workers resulting from high job insecurity and disparities in employment conditions. Although the Korean government provides several corporate welfare programs, public assistance for nonregular workers is still in its early stages. In addition, employment assistance programs that address high stress and mental health problems among nonregular workers by providing counseling services and training should be expanded to more workplaces.
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ACCEPTED MANUSCRIPT 36. Nettelbladt P, Hansson L, Stefansson CG, Borgquist L, Nordström G. Test characteristics of the Hopkins Symptom Check List-25 (HSCL-25) in Sweden, using the Present State Examination (PSE-9) as a caseness criterion. Soc Psychiatry Psychiatr Epidemiol. 1993;28(3):130-133. 37. McKelvey RS, Webb JA. A prospective study of psychological distress related to refugee Downloaded by [Australian National University] at 05:13 08 November 2015
camp experience. Aust N Z J Psychiatry. 1997;31(4):549-554. 38. Mollica RF, Wyshak G, de Marneffe D, Khuon F, Lavelle J. Indochinese version of the Hopkins Symptom Checklist-25: a screening instrument for the psychiatric care of refugees. Am J Psychiatry. 1987;144(4):497-500. 39. Chang SJ, Koh SB, Kang D, et al. Developing an occupational stress scale for Korean employees [in Korean]. Korean J Occup Environ Med. 2005;17(4):297-317. 40. Simmons LA, Swanberg JE. Psychosocial work environment and depressive symptoms among US workers: comparing working poor and working non-poor. Soc Psychiatry Psychiatr Epidemiol. 2009;44(8):628-635. 41. Maciejewski PK, Prigerson HG, Mazure CM. Sex differences in event-related risk for major depression. Psychol Med. 2001;31(4):593-604. 42. Marcotte DE, Wilcox-Gök V, Redmon DP. Prevalence and patterns of major depressive disorder in the United States labor force. J Ment Health Policy Econ. 1999;2(3):123-131. 43. Leibson CL, Garrard J, Nitz N, et al. The role of depression in the association between selfrated physical health and clinically defined illness. Gerontologist. 1999;39(3):291-298. 44. Shipler DK. The Working Poor: Invisible in America. New York, NY: Vintage Books; 2005.
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ACCEPTED MANUSCRIPT 45. Kim AE, Park I. Changing trends of work in South Korea: the rapid growth of underemployment and job insecurity. Asian Surv. 2006;46(3):437-456. 46. Bae HS. A study on the distinction of non-obligatory welfare services between standard and non-standard workers [in Korean]. Soc Welf Policy, 2005;21(4):217-237. 47. Ban JH. Welfare disparity by employment type [in Korean]. Mon Labor Rev. Downloaded by [Australian National University] at 05:13 08 November 2015
2006;March:28-38.
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ACCEPTED MANUSCRIPT Table 1. Sociodemographic and Psychosocial Characteristics of the Sample, 2012 (N = 333) Variable
Totala
333
n
HSCL-25
HSCL-25
≥ 1.75a
< 1.75a
118
χ2
p
215
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Sociodemographic Variables Gender Male
185 (55.6)
53 (28.6)
132 (71.4)
Female
148 (44.4)
65 (43.9)
83 (56.1)
Age (years) ≤ 29
39 (11.7)
7 (17.9)
32 (82.1)
30–39
65 (19.5)
12 (18.5)
53 (81.5)
40–49
82 (24.6)
33 (40.2)
49 (59.8)
50–59
79 (23.7)
37 (46.8)
42 (53.2)
≥ 60
68 (20.4)
29 (42.6)
39 (57.4)
Education Middle school or less High school College or more
91 (27.3)
48 (52.7)
43 (47.3)
151 (45.3)
55 (36.4)
96 (63.6)
91 (27.3)
15 (16.5)
Married/partnered Separated/divorced/widowed
89 (26.7)
20 (22.5)
69 (77.5)
200 (60.1)
75 (37.5)
125 (62.5)
44 (13.2)
23 (52.3)
21 (47.7)
23
.004
20.260
< .001
26.271
< .001
12.362
.002
76 (83.5)
Marital status Never married
8.380
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ACCEPTED MANUSCRIPT Type of nonregular employment Limited-term contract or part-time
159 (47.7)
56 (35.2)
103 (64.4)
Atypical
174 (52.3)
62 (35.6)
112 (64.8)
0.006
.937
18.990
< .001
31.354
< .001
Psychosocial Variables Self-perceived economic status Downloaded by [Australian National University] at 05:13 08 November 2015
Lower/middle-lower class Middle/middle-upper/upper class
243 (73.0)
103 (42.4)
140 (56.7)
90 (27.0)
15 (16.7)
75 (83.3)
Self-rated health Very bad/bad Similar to others/good/very good
98 (29.4)
57 (58.2)
41 (41.8)
235 (70.5)
61 (26.0)
174 (74.0)
Abbreviation: HSCL-25, Hopkins Symptom Checklist-25. a
n (%)
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ACCEPTED MANUSCRIPT Table 2. Association between Job Stress and Mental Health, 2012 (N = 333)
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Job Stress Subscale
Totala
HSCL-25
HSCL-25
≥ 1.75a
< 1.75a
t
p
Job demands
44.4 (17.0)
48.9 (17.6)
41.9 (16.1)
3.635
< .001
Insufficient job control
62.8 (21.1)
69.7 (19.3)
59.0 (21.2)
4.508
< .001
Inadequate social support
46.7 (21.3)
53.7 (20.2)
42.8 (20.9)
4.644
< .001
Job insecurity
47.4 (26.1)
57.4 (24.5)
42.0 (25.3)
5.386
< .001
Organizational system
54.0 (20.7)
60.3 (19.3)
50.5 (20.7)
4.245
< .001
Lack of rewards
54.9 (21.8)
63.6 (20.9)
50.1 (20.8)
5.641
< .001
Occupational climate
39.3 (18.0)
42.0 (18.1)
37.8 (17.8)
2.047
.041
a
M (SD)
Note. Calculation of job stress score (adjusted to a scale of 0 to 100): scores of each subscale = ([score-number of items]/[maximum score-number of items] × 100); score of total job stress = (total scores of seven subscales/7).
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ACCEPTED MANUSCRIPT Table 3. Logistic Regression Analysis of Job Stress and Mental Health among Nonregular Workers, Controlling for Sociodemographic and Psychosocial Characteristics, 2012 (N = 333) Variable
OR
95% CI
p
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Sociodemographic Variables Gender Male Female
Ref 2.352
1.214, 4.557
.011
Age (years) ≤ 29
Ref
30–39
0.753
0.214, 2.642
ns
40–49
1.635
0.407, 6.572
ns
50–59
2.157
0.504, 9.232
ns
≥ 60
1.327
0.285, 6.180
ns
Middle school or less
3.222
1.178, 8.813
.023
High school
2.336
1.063, 5.133
.035
Education
College or more
Ref
Marital status Never married
Ref
Married/partnered
0.497
0.186, 1.332
ns
Separated/divorced/widowed
0.533
0.156, 1.818
ns
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ACCEPTED MANUSCRIPT Type of nonregular employment Limited-term contract or part-time Atypical
1.370
0.727, 2.583
ns
1.287, 5.516
.008
1.493, 5.192
.001
Ref
Psychosocial Variables Self-perceived economic status Downloaded by [Australian National University] at 05:13 08 November 2015
Lower/middle-lower class Middle/middle-upper/upper class
2.664 Ref
Self-rated health Very bad/bad Similar to others/good/very good
2.784 Ref
Job Stress Variables Job demands
1.017
0.997, 1.037
ns
Insufficient job control
0.998
0.980, 1.017
ns
Inadequate social support
1.002
0.985, 1.020
ns
Job insecurity
1.020
1.007, 1.032
.002
Organizational system
1.002
0.983, 1.020
ns
Lack of rewards
1.028
1.009, 1.048
.005
Occupational climate
1.007
0.989, 1.025
ns
Abbreviations: Ref, reference category; ns, not significant.
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ISSN: 1933-8244 (Print) 2154-4700 (Online) Journal homepage: http://www.tandfonline.com/loi/vaeh20
Job Stress and Mental Health among Nonregular Workers in Korea: What Dimensions of Job Stress are Associated with Mental Health? Soo Kyung Park Ph.D, Min-Kyoung Rhee Ph.D & Michàlle Mor Barak Ph.D To cite this article: Soo Kyung Park Ph.D, Min-Kyoung Rhee Ph.D & Michàlle Mor Barak Ph.D (2014): Job Stress and Mental Health among Nonregular Workers in Korea: What Dimensions of Job Stress are Associated with Mental Health?, Archives of Environmental & Occupational Health, DOI: 10.1080/19338244.2014.997381 To link to this article: http://dx.doi.org/10.1080/19338244.2014.997381
Accepted author version posted online: 16 Dec 2014.
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Date: 08 November 2015, At: 05:13
ACCEPTED MANUSCRIPT Job Stress and Mental Health among Nonregular Workers in Korea: What Dimensions of Job Stress are Associated with Mental Health? Soo Kyung Park, Ph.D; Min-Kyoung Rhee, Ph.D.; Michàlle Mor Barak, Ph.D Acknowledgement: Soo Kyung Park, Ph.D gratefully acknowledges the LG YONAM foundation for its financial support of her sabbatical stay at University of Southern California. This work was supported by the LG YONAM foundation grants in 2011.
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Author Affiliations: Department of Social Welfare, Daejin University, Pocheon-si, South Korea (S.K. Park); School of Social Work, University of Southern California, Los Angeles (M.K. Rhee and M. Mor Barak). Corresponding Author: Min-Kyoung Rhee, School of Social Work, University of Southern California, 669 W. 34th street, Los Angeles, CA 90089-0411 email: [email protected] ABSTRACT Although nonregular workers experience higher job stress, poorer mental health, and different job stress dimensions relative to regular workers, little is known about which job stress dimensions are associated with poor mental health among nonregular workers. This study investigated the association between job stress dimensions and mental health among Korean nonregular workers. Data were collected from 333 nonregular workers in Seoul and Gyeonggi Province and logistic regression analysis was conducted. Results of the study indicated that high job insecurity and lack of rewards had stronger associations with poor mental health than other dimensions of job stress when controlling for sociodemographic and psychosocial variables. It is important for the government and organizations to improve job security and reward systems to reduce job stress among nonregular workers and ultimately alleviate their mental health issues. KEYWORDS: job stress, mental health, nonregular workers, Korea
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ACCEPTED MANUSCRIPT INTRODUCTION According to the U.S. National Institute for Occupational Safety and Health, job stress is defined as “the harmful physical and emotional responses that occur when the requirements of the job do not match the capabilities, resources, or needs of the worker.”1 Approximately 41% to 83% of employees experience job stress,1-4 and rates have increased substantially during the last Downloaded by [Australian National University] at 05:13 08 November 2015
few decades partly due to intensified workloads, high job insecurity, downgraded job quality, and work–family conflict.2,4,5 Although job stress is an important issue for both organizations and employees due to its various adverse consequences,3,6-11 it may be more of a concern for nonregular workers who experience high job insecurity, low wages, and lack of access to social protection and employment benefits.12 In South Korea (hereafter Korea), nonregular workers are defined as individuals who engage in limited-term contract, part-time, or atypical employment including dispatch, subcontract, independent contract, on-call or daily, and tele- or home-based work.13,14 It is estimated that between 33.3% and 47.8% of wage workers are nonregular workers in Korea15,16 marking one of the highest proportions among Organization for Economic Co-operation and Development (OECD) countries.17 Korea’s economic crisis in 1997 and the implementation of neoliberal economic reforms not only substantially increased the number of nonregular workers but also increased wage inequality18 and job insecurity compared to EU15 or OECD countries.19 Korean nonregular workers earned only 57% as much per hour as regular workers in 2010,20 and their average tenure was 2.24 years compared to 8.17 years for regular workers.16 Moreover, they have limited opportunities for promotion, job training, access to social insurance, and other employee benefits such as retirement annuities, bonuses, overtime pay, and paid leave.15,20 These
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ACCEPTED MANUSCRIPT disproportionate employment challenges are likely to create high job stress for nonregular workers, which in turn may negatively affect their mental health or psychological well-being. Previous research has consistently documented empirical evidence of higher job stress and poorer mental health among nonregular workers compared to regular workers.21-26 Research has indicated that nonregular workers experience not only significantly higher job stress than Downloaded by [Australian National University] at 05:13 08 November 2015
regular workers but also different job stress factors.21,22,24 Whereas nonregular workers experience significantly higher job stress due to high job demand, high job insecurity, insufficient job control, lack of rewards, low social support, and lack of fairness or support in the organizational system,21,22,24 regular workers experience job stress due to high job demand and discomfort in occupational climate.22 Discomfort in occupational climate specifically refers to potential stress that can be caused by collective and authoritarian Korean organizational culture, inconsistent job requirements, and gender discrimination. Previous research also has indicated that nonregular workers experienced higher psychological distress such as depression compared to regular workers.23,25,26 Cho and colleagues23 examined job stress and depression among 8,522 workers in 329 workplaces in Korea and found that the prevalence of depression among nonregular workers was significantly higher than that of regular workers. Evidence of the higher prevalence of job stress and mental health problems among nonregular workers suggests the need for more in-depth examination of nonregular workers’ job stress and its relationship with mental health. However, there is a dearth of empirical evidence regarding the relationship between job stress dimensions and mental health specifically related to nonregular workers. Studies that examined differences in job stress dimensions between nonregular and regular workers did not further examine the relationship between job stress and
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ACCEPTED MANUSCRIPT mental health.21,24 In addition, most empirical evidence of the positive relationship between job stress and psychological distress has been related to workers in general.23,26-28 Although Jeon and colleagues22 examined the association between job stress dimensions and psychosocial aspects among 361 hospital workers, their analysis was limited to bivariate examination of correlations. To fill this gap in the literature, this study aimed to estimate the potential effects of Downloaded by [Australian National University] at 05:13 08 November 2015
subdimensions of job stress on mental health by examining which components of job stress were more strongly associated with mental health among nonregular workers in Korea. Two leading theoretical models in job stress research, Karasek’s job demand–control (JDC) model and Siegrist’s effort–reward imbalance (ERI) model, were used as our theoretical framework. The JDC model postulates that high job stress is generated by a combination of high job demands and low job control.29 The ERI model, on the other hand, posits that high job stress is an outcome of a mismatch or lack of reciprocity between high investment of effort (high demands and obligations at work) and low rewards received (lack of promotion opportunities, job insecurity).30 Empirical studies that used these models have indicated that low job control, high demands at work, and effort–reward imbalance are significant factors related to depression and psychosocial distress.31-34 Moreover, low job control and effort–reward imbalance are stronger predictors of mental health problems for employees with high job insecurity.33 Other studies that examined job stress and mental health among Korean employees found that subdimensions of job stress such as job demands, inadequate social support, job insecurity, lack of rewards, and discomfort in occupational climate were associated with higher risk of depression.23,26
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ACCEPTED MANUSCRIPT Based on these two theoretical models of job stress and a review of existing literature, we developed the following hypotheses to estimate the potential effects of subdimensions of job stress on mental health. H1: High job demands are associated with poor mental health. H2: Insufficient job control is associated with poor mental health. Downloaded by [Australian National University] at 05:13 08 November 2015
H3: Inadequate social support is associated with poor mental health. H4: High job insecurity is associated with poor mental health. H5: Low level of fairness or support in the organizational system is associated with poor mental health. H6: Lack of rewards is associated with poor mental health. H7: Discomfort in occupational climate is associated with poor mental health. Based on the aforementioned employment conditions specific to Korean nonregular workers, i.e., high job insecurity, low pay, and less access to social insurance and employment benefits, we also developed the following hypothesis to examine which subscales of job stress are more strongly associated with mental health among nonregular workers in Korea. H8: High job insecurity and lack of rewards are more strongly associated with poor mental health than other dimensions of job stress when controlling for sociodemographic and psychosocial variables. METHODS Study population Study participants were 333 nonregular workers in Seoul and Gyeonggi Province, one of the largest metropolitan areas in Korea. The definition of nonregular workers for this study was
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ACCEPTED MANUSCRIPT based on type of employment and included contingent and part-time workers, dispatched workers indirectly employed through temporary work agencies, temporary help agency workers, independent contractors, on-call and daily workers, and teleworkers and home-based workers. Purposive sampling was employed to recruit participants by sending requests for cooperation to individuals in charge of a university, a district office, a company in the service industry, and three Downloaded by [Australian National University] at 05:13 08 November 2015
apartment buildings to describe the nature of our study and the survey. After receiving permission from these agencies, we visited employees commonly identified as nonregular workers by type of employment, such as cleaning workers, big-box store cashiers, apartment guards, and other contingent and part-time workers. We also confirmed whether or not they were nonregular workers and their willingness to participate. Informed consent was verbally obtained from participants after a full explanation of the purpose of the research and confidentiality issues. Questionnaires were distributed to nonregular workers who had agreed to participate in the selfadministered survey. Participants were assured of the confidentiality and anonymity of their responses. Each participant who answered the questionnaire was given a multiuse coupon (with a value of $5) as a reward. The final analysis relied on information from 333 questionnaires collected in May 2012. This study was approved under the coded data determination by [blinded for review]. Measurement Dependent variable Mental health was assessed using the Hopkins Symptom Checklist (HSCL-25), which is a 25-item version of the Symptom Check List-90. This self-report inventory assesses anxiety (10 items) and depression (15 items) on a 4-point scale (1 = not at all, 2 = a little, 3 = quite a bit, and
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ACCEPTED MANUSCRIPT 4 = extremely). The instrument measures to what extent study participants were bothered by certain symptoms during the past month, including feeling fearful, blaming oneself for things, crying easily, having a poor appetite, and feeling no interest in things, etc. A total score was calculated by averaging all 25 items, with higher scores indicating more psychiatric or affective symptoms. The HSCL-25 scale can be a screening tool for psychiatric problems, with scores Downloaded by [Australian National University] at 05:13 08 November 2015
greater than or equal to 1.75 indicating a probable need for psychiatric treatment.35,36 In this study, we dichotomized mental health using the cutoff point of 1.75 to identify individuals with clinically significant psychiatric problems. Individuals who scored 1.75 or higher in HSCL-25 were classified in a mental health risk group and those who scored less than 1.75 were categorized in a nonrisk group. This measure has been found to be valid in cross-cultural settings,35,37,38 and Cronbach’s alpha of the overall scale in this study was .96. Independent variable Job stress was measured using 24 items of the short form of the Korean Occupational Stress Scale (KOSS-SF), a self-report questionnaire for estimating unique and specific occupational stressors among Korean employees. Chang and his colleagues39 validated the reliability of the KOSS in a nationwide epidemiological study conducted in Korea. The subscales of the KOSS-SF used in this study were job demands (4 items, α = .58), insufficient job control (4 items, α = .78), inadequate social support (3 items, α = .75), job insecurity (2 items, α = .72), organizational system (4 items, α = .79), lack of rewards (3 items, α = .76), and occupational climate (4 items, α = .62). Each item was rated on a Likert scale from 1 (not at all) to 4 (very much). Job stress scores for each subscale were calculated using a formula proposed by Chang et al39: ([obtained score-number of items]/[maximum expected score-number of items] × 100) and
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ACCEPTED MANUSCRIPT adjusted to a scale of 0 to 100. Positive items were reverse coded so that higher scores indicated higher job stress. For further description of subscale items, see Park et al.26 Control variables Control variables include gender, age (≤ 29, 30–39, 40–49, 50–59, ≥ 60), education (middle school or less, high school, college or more), marital status (never married, married or Downloaded by [Australian National University] at 05:13 08 November 2015
partnered, separated/divorced/ widowed), type of nonregular employment (atypical vs. limitedterm contract or part-time), self-perceived economic status (lower/middle-lower class vs. middle/middle-upper/upper class), and self-rated health (very bad/bad vs. similar to others/good/very good). Statistical analyses Pearson’s χ2 tests were used to examine the relationships between general characteristics and mental health. T-tests were used to examine differences in the seven subscales of job stress between the mental health risk group, whose members scored 1.75 or higher on the HSCL-25, and the nonrisk group, whose members scored less than 1.75. Finally, logistic regression was used to estimate associations between job stress and mental health after controlling for sociodemographic and psychosocial variables. Rates of missing data were very low for all measures in the study, and cases with missing data were excluded from the analyses. Data were analyzed using SPSS 12.0 software.
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ACCEPTED MANUSCRIPT RESULTS Descriptive statistics Sociodemographic and psychosocial characteristics of the sample are presented in Table 1; 55.6% of the participants were men and approximately 25% of respondents were in their 40s. A majority of participants had received a high school education or higher, were married, Downloaded by [Australian National University] at 05:13 08 November 2015
perceived themselves as lower class in terms of their economic status, and reported that they had similar or better health compared to others. Regarding employment status, 47.7% were contingent or part-time workers who were directly employed by their employers, whereas 52.3% were dispatched workers who were indirectly employed through temporary work agencies. [Insert Table 1 here] Bivariate analyses We defined the mental health risk group as HSCL-25 ≥ 1.75 and the nonrisk group as HSCL-25 < 1.75. Slightly more than one third of the respondents (35.4%) belonged to the mental health risk group, indicating that they were at significant risk of psychiatric problems and should receive further diagnostic assessment. The results of χ2 tests in Table 1 indicated that there were significant differences between the mental health risk and nonrisk groups with regard to all sociodemographic and psychosocial variables included in the study, except type of nonregular employment. As shown in Table 1, women, those in older age groups, those with a middle school education or less, those who were widowed, separated, or divorced, those who perceived their economic status as lower or middlelower class, and those who rated their health worse compared to others were more likely to have poorer mental health, as evidenced by a significantly higher proportion of HSCL-25 scores above
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ACCEPTED MANUSCRIPT 1.75. No significant associations were found between mental health and type of nonregular employment. [Insert Table 2 here] The mean scores for the seven subscales of job stress by subgroup are presented in Table 2. Mean scores for all subscales of job stress were statistically significantly higher in the mental Downloaded by [Australian National University] at 05:13 08 November 2015
health risk group than the nonrisk group. That is, participants above the HSCL-25 cutoff point perceived that they had more job demands, less job control, less social support, more job insecurity, a less fair organizational system, fewer rewards, and more discomfort in occupational climate. Multivariate Analysis Table 3 presents the results of multivariate analysis examining sociodemographic and psychosocial characteristics and subscales of job stress associated with mental health status. Women had a greater likelihood of being at risk of psychiatric problems than men. Those who received a middle school education or less or a high school education were more likely to be at risk of psychiatric problems than those with a college education or higher. Those who perceived their economic status as low were more likely to score above the HSCL-25 cutoff point than those who did not. Self-rated health was also strongly associated with mental health. Those who rated themselves as less healthy were more likely to score above the HSCL-25 cutoff point than those who assessed themselves as healthy compared to others. Among job stress subscales, job insecurity and lack of rewards had statistically significant relationships with risk of psychiatric problems among nonregular workers. [Insert Table 3 here]
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ACCEPTED MANUSCRIPT DISCUSSION The purpose of this study was to examine which components of job stress were stronger predictors of mental health among nonregular workers in Korea. To achieve this aim, we hypothesized that (1) high job demands, insufficient job control, inadequate social support, high job insecurity, low level of fairness or support in organizational system, lack of rewards, and Downloaded by [Australian National University] at 05:13 08 November 2015
discomfort in occupational climate would be associated with poor mental health and that (2) high job insecurity and lack of rewards would have stronger associations with poor mental health than other dimensions of job stress when controlling for sociodemographic and psychosocial variables. Our analysis showed 35.4% of the study sample belonged to the mental health risk group, scoring 1.75 or higher on the HSCL-25. This indicates that more than one third of respondents were experiencing depression, anxiety, or somatic symptoms that require psychiatric care, a relatively higher proportion than reported in previous research.23,26 Such a high prevalence of mental health problems among nonregular workers may be associated with high job stress caused by job insecurity or low pay. As expected, this study found high job insecurity and lack of rewards to be the only predictors of poor mental health after controlling for covariates, although all seven subscales of job stress were associated with mental health in bivariate analyses. This result can be better understood in the context of the employment conditions of nonregular workers in Korea. As stated in the introduction, high job insecurity, income disparity, lack of opportunities for promotion, and poor access to employment benefits are among the most critical issues for nonregular workers in Korea. Working in highly insecure positions with low pay and limited employment benefits can create high job stress for nonregular workers, which may
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ACCEPTED MANUSCRIPT negatively affect their mental health. Moreover, lack of a social security system and labor market policies to protect nonregular workers may aggravate their job stress and mental health problems. The results of our study are consistent with previous research in the literature. A study by Simmons and Swanberg40 examined the effects of environmental factors, including job type, decision making, work flexibility, support from supervisors and coworkers, and job insecurity, Downloaded by [Australian National University] at 05:13 08 November 2015
on depression levels by economic status. They reported that job insecurity was the only predictor of depression among workers with low economic status. Although depression among those with better economic status was significantly alleviated by support from supervisors and coworkers, those with low economic status and high job insecurity still reported depression after receiving support from supervisors and coworkers and increased work flexibility.40 This indicates that high job insecurity is a significant stressor that harms the mental health of individuals of lower economic status who are mostly nonregular workers. In terms of lack of rewards, the mental health of nonregular workers can be threatened because they typically earn low wages and receive less protection from social insurance despite their economic activity. Because income is not only a representative reward system but also one that provides basic resources to maintain a livelihood, nonregular workers who are economically underprivileged may have particularly high stress that can threaten their mental health. Similar to our results, previous research indicated that a lack of rewards is a significant job stressor for nonregular workers24 and that effort–reward imbalance has a stronger effect on depression among employees with high job insecurity.33 On the other hand, studies that examined specific aspects of job stress that were associated with depression using the KOSS among Korean employees had different results than
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ACCEPTED MANUSCRIPT the present study. According to a study by Cho and colleagues23 of 8,522 Korean employees nationwide, high job demand, insufficient job control, job insecurity, lack of rewards, inadequate social support, and discomfort in occupational climate were significant predictors of depression, and inadequate social support and discomfort in occupational climate were stronger risk factors. However, 81.4% of those surveyed by Cho and his colleagues23 were regular workers and the Downloaded by [Australian National University] at 05:13 08 November 2015
researchers did not distinguish between regular or nonregular workers in their analysis. In addition, because regular workers maintain relatively longer tenure of employment, they may be more exposed to collective Korean organizational culture, such as closely interacting with colleagues and supervisors or dining together with their team members after work. Thus, inadequate social support and discomfort in occupational climate can be significant job stressors for these employees. However, nonregular workers tend to have much shorter tenure than regular workers and may have different values or expectations about relationships with colleagues or supervisors, as well as collective culture. Thus their job stressors may be different than regular workers. Park and colleagues26 examined 3,103 Korean full-time employees in small- and medium-size enterprises and found that job insecurity was the strongest predictor of depression for both men and women, but a lack of rewards was associated with depressive symptoms only for men. These findings, along with ours, confirm that job insecurity is a strong job stressor that adversely affects the mental health of both full-time employees in small- and medium-size enterprises and nonregular workers. In addition, the finding that a lack of rewards was associated with depressive symptoms only for men26 suggests that a lack of rewards can act as a powerful risk factor for depression even for full-time employees when they are economically underprivileged and for men who are often expected to play a role as the main breadwinner.
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ACCEPTED MANUSCRIPT However, this study did not provide specific information on nonregular workers because it included only full-time employees. Our study results also showed that sociodemographic characteristics such as gender and education and psychosocial variables such as self-perceived economic status and self-rated health were associated with a higher prevalence of mental health problems. Women and those Downloaded by [Australian National University] at 05:13 08 November 2015
with lower education levels, lower perceived economic status, and lower self-rated health reported greater risk of adverse mental health problems. These results are supported by previous studies that found women are typically more vulnerable to depression or anxiety,41,42 lower-class workers are more depressed compared to workers in higher economic classes,40 and self-rated health is negatively related to mental health.43 In particular, workers with lower economic status are known to experience high stress when performing work duties because they often have low education levels and poor technical skills coupled with high job insecurity.44 In terms of economic status, it is possible that nonregular workers’ perceptions of their economic status may have played a role in the association between job stress and mental health rather than their actual economic status, because all study participants were nonregular workers who tended to be economically underprivileged. There are several limitations in the current study that need to be considered when interpreting the study results. First, the study employed a cross-sectional design, preventing the assessment of causal relationships among variables. The possibility of reverse causation should be considered. Second, measures of job stress and mental health were based on self-reported data and are subject to self-report bias. For example, Koreans tend to address psychological distress inwardly and have strong stigma against mental illness, and therefore may report less job stress
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ACCEPTED MANUSCRIPT or mental health problems. Third, although we acknowledge that subdimensions of job stress and their relationship with mental health can vary according to certain sociodemographic characteristics such as gender, age, and education because of different work experiences, our analyses did not consider such potential differences due to the limited number of participants in each subgroup. Future studies of job stress and mental health outcomes should consider Downloaded by [Australian National University] at 05:13 08 November 2015
examining whether the association of job stress with mental health is specific to certain sociodemographic characteristics. Fourth, although we focused specifically on nonregular workers based on several rationales, a comparison between nonregular and regular workers, examining how the association of subdimensions of job stress differed by employment type, may have been more informative. This can be addressed in future studies by including a sample of regular workers. In addition, researchers should examine how or whether differences between the two groups change depending on how nonregular workers are defined. Because there is no universal definition of nonregular workers, the composition of regular and nonregular workers can vary, which may affect research results. Despite these limitations, the results of our study provide significant implications for occupational health policy and practice. First, more sophisticated regulations and laws to protect nonregular workers’ rights and quality of employment need to be developed. Because many employers have hired nonregular workers to avoid high labor costs and the difficulty of laying off regular workers, nonregular workers often experience high job insecurity and lack of rewards. Although nonregular employment has become prevalent in Korea, laws and regulations that protect the rights of nonregular workers are relatively weak.45 Second, the coverage of nonregular workers by the social safety net needs to be increased. The social insurance system in
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ACCEPTED MANUSCRIPT Korea was originally designed for regular workers and has limitations in terms of support for nonregular workers. Because most fringe benefits provided by employers depend on their ability to pay for those benefits, nonregular workers and employees at small- and medium-size enterprises, which account for approximately 90% of all workers in Korea, have substantial limitations in terms of receiving work benefits.46,47 Third, diverse interventions need to be Downloaded by [Australian National University] at 05:13 08 November 2015
developed to prevent and manage high job stress among nonregular workers resulting from high job insecurity and disparities in employment conditions. Although the Korean government provides several corporate welfare programs, public assistance for nonregular workers is still in its early stages. In addition, employment assistance programs that address high stress and mental health problems among nonregular workers by providing counseling services and training should be expanded to more workplaces.
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ACCEPTED MANUSCRIPT 36. Nettelbladt P, Hansson L, Stefansson CG, Borgquist L, Nordström G. Test characteristics of the Hopkins Symptom Check List-25 (HSCL-25) in Sweden, using the Present State Examination (PSE-9) as a caseness criterion. Soc Psychiatry Psychiatr Epidemiol. 1993;28(3):130-133. 37. McKelvey RS, Webb JA. A prospective study of psychological distress related to refugee Downloaded by [Australian National University] at 05:13 08 November 2015
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ACCEPTED MANUSCRIPT 45. Kim AE, Park I. Changing trends of work in South Korea: the rapid growth of underemployment and job insecurity. Asian Surv. 2006;46(3):437-456. 46. Bae HS. A study on the distinction of non-obligatory welfare services between standard and non-standard workers [in Korean]. Soc Welf Policy, 2005;21(4):217-237. 47. Ban JH. Welfare disparity by employment type [in Korean]. Mon Labor Rev. Downloaded by [Australian National University] at 05:13 08 November 2015
2006;March:28-38.
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ACCEPTED MANUSCRIPT Table 1. Sociodemographic and Psychosocial Characteristics of the Sample, 2012 (N = 333) Variable
Totala
333
n
HSCL-25
HSCL-25
≥ 1.75a
< 1.75a
118
χ2
p
215
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Sociodemographic Variables Gender Male
185 (55.6)
53 (28.6)
132 (71.4)
Female
148 (44.4)
65 (43.9)
83 (56.1)
Age (years) ≤ 29
39 (11.7)
7 (17.9)
32 (82.1)
30–39
65 (19.5)
12 (18.5)
53 (81.5)
40–49
82 (24.6)
33 (40.2)
49 (59.8)
50–59
79 (23.7)
37 (46.8)
42 (53.2)
≥ 60
68 (20.4)
29 (42.6)
39 (57.4)
Education Middle school or less High school College or more
91 (27.3)
48 (52.7)
43 (47.3)
151 (45.3)
55 (36.4)
96 (63.6)
91 (27.3)
15 (16.5)
Married/partnered Separated/divorced/widowed
89 (26.7)
20 (22.5)
69 (77.5)
200 (60.1)
75 (37.5)
125 (62.5)
44 (13.2)
23 (52.3)
21 (47.7)
23
.004
20.260
< .001
26.271
< .001
12.362
.002
76 (83.5)
Marital status Never married
8.380
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ACCEPTED MANUSCRIPT Type of nonregular employment Limited-term contract or part-time
159 (47.7)
56 (35.2)
103 (64.4)
Atypical
174 (52.3)
62 (35.6)
112 (64.8)
0.006
.937
18.990
< .001
31.354
< .001
Psychosocial Variables Self-perceived economic status Downloaded by [Australian National University] at 05:13 08 November 2015
Lower/middle-lower class Middle/middle-upper/upper class
243 (73.0)
103 (42.4)
140 (56.7)
90 (27.0)
15 (16.7)
75 (83.3)
Self-rated health Very bad/bad Similar to others/good/very good
98 (29.4)
57 (58.2)
41 (41.8)
235 (70.5)
61 (26.0)
174 (74.0)
Abbreviation: HSCL-25, Hopkins Symptom Checklist-25. a
n (%)
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ACCEPTED MANUSCRIPT Table 2. Association between Job Stress and Mental Health, 2012 (N = 333)
Downloaded by [Australian National University] at 05:13 08 November 2015
Job Stress Subscale
Totala
HSCL-25
HSCL-25
≥ 1.75a
< 1.75a
t
p
Job demands
44.4 (17.0)
48.9 (17.6)
41.9 (16.1)
3.635
< .001
Insufficient job control
62.8 (21.1)
69.7 (19.3)
59.0 (21.2)
4.508
< .001
Inadequate social support
46.7 (21.3)
53.7 (20.2)
42.8 (20.9)
4.644
< .001
Job insecurity
47.4 (26.1)
57.4 (24.5)
42.0 (25.3)
5.386
< .001
Organizational system
54.0 (20.7)
60.3 (19.3)
50.5 (20.7)
4.245
< .001
Lack of rewards
54.9 (21.8)
63.6 (20.9)
50.1 (20.8)
5.641
< .001
Occupational climate
39.3 (18.0)
42.0 (18.1)
37.8 (17.8)
2.047
.041
a
M (SD)
Note. Calculation of job stress score (adjusted to a scale of 0 to 100): scores of each subscale = ([score-number of items]/[maximum score-number of items] × 100); score of total job stress = (total scores of seven subscales/7).
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ACCEPTED MANUSCRIPT Table 3. Logistic Regression Analysis of Job Stress and Mental Health among Nonregular Workers, Controlling for Sociodemographic and Psychosocial Characteristics, 2012 (N = 333) Variable
OR
95% CI
p
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Sociodemographic Variables Gender Male Female
Ref 2.352
1.214, 4.557
.011
Age (years) ≤ 29
Ref
30–39
0.753
0.214, 2.642
ns
40–49
1.635
0.407, 6.572
ns
50–59
2.157
0.504, 9.232
ns
≥ 60
1.327
0.285, 6.180
ns
Middle school or less
3.222
1.178, 8.813
.023
High school
2.336
1.063, 5.133
.035
Education
College or more
Ref
Marital status Never married
Ref
Married/partnered
0.497
0.186, 1.332
ns
Separated/divorced/widowed
0.533
0.156, 1.818
ns
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ACCEPTED MANUSCRIPT Type of nonregular employment Limited-term contract or part-time Atypical
1.370
0.727, 2.583
ns
1.287, 5.516
.008
1.493, 5.192
.001
Ref
Psychosocial Variables Self-perceived economic status Downloaded by [Australian National University] at 05:13 08 November 2015
Lower/middle-lower class Middle/middle-upper/upper class
2.664 Ref
Self-rated health Very bad/bad Similar to others/good/very good
2.784 Ref
Job Stress Variables Job demands
1.017
0.997, 1.037
ns
Insufficient job control
0.998
0.980, 1.017
ns
Inadequate social support
1.002
0.985, 1.020
ns
Job insecurity
1.020
1.007, 1.032
.002
Organizational system
1.002
0.983, 1.020
ns
Lack of rewards
1.028
1.009, 1.048
.005
Occupational climate
1.007
0.989, 1.025
ns
Abbreviations: Ref, reference category; ns, not significant.
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