Gender and educational level modify the relationship between workplace mistreatment and health problems: a comparison between South Korea and EU countries

Abstract

Objectives: This study investigated effects of workers' cultural and personal characteristics on the relationship between workplace mistreatment and health problems in both South Korea and EU Countries. Methods: Data were obtained from nationally representative interview surveys: the third Korean Working Conditions Survey (KWCS) in 2011 (50,032 participants) and fifth European Working Conditions Survey (EWCS) in 2010 (41,302 participants). The Pressure-State-Response model was adapted to explore differences in the relationship between mistreatment and health problems according to country, and logistic regression analysis was used after stratification of moderating factors. Workplace mistreatment, such as discrimination, violence, harassment, and self-reported health problems, were assessed by gender and educational level. Results: Among KWCS participants, there were 4,321 victims (14.70%) of workplace mistreatment; among EWCS participants, there were 5,927 victims (17.89%). There was a significant positive association between workplace mistreatment and self-reported health problems. A stronger association was found among workers with higher educational levels in Korea (2- to 4-fold higher odds for mental and physical health problems), but there was no significant difference by education level in workers of EU Countries. Female Koreans who worked alone had a higher risk of health problems related to workplace mistreatment than other gender compositions in the workplace (the OR for psychological symptoms reached 6.631). In contrast, the gender composition of the work place did not significantly affect EU workers. Conclusions: Workplace mistreatment is significantly associated with physical and mental health problems, especially among workers with higher educational levels and females who work alone in Korea.

(J Occup Health 2015; 57: 427–437)

Introduction

Over the past two decades, workplace mistreatment has been recognized as a serious problem within the working environment, and this relatively new research topic has now been studied extensively in several European countries^1–4). Even so, there is still limited information about workplace mistreatment in Asia, although in recent years, Asian researchers have increasingly focused on workplace mistreatment as an important social stressor in work contexts^{5, 6)}.

The scope and terminology of workplace mistreatment varies across the discipline, incorporating workplace discrimination, violence, and bullying. Workplace discrimination refers to actions of institutions and/or individuals within them that lead to unfair terms and conditions that systematically impair the ability of group members to work⁷⁾. Violence can be defined as any form of aggressive behavior aimed toward the goal of harming another human being, and it can be both psychological and physical in nature. In the extreme form, violence may involve the use of physical force to harm or damage persons or property or to interfere with personal rights or freedom²⁾. Another form of aggressive behavior at work is bullying. Workplace bullying includes both physical and nonphysical actions that offend or socially exclude a worker or group of workers; some researchers specify that this definition must include an intent to harm either the individual or the organization⁸⁾. For the purpose of this paper, we defined workplace mistreatment to include workplace-related discrimination, violence, abuse, or harassment.

Cultural differences in construing the meaning of specific behaviors make it harder to determine which behaviors are abusive⁹⁾. Less attention has been paid to national differences in mistreatment, though some researchers have pointed out the problems of using questionnaires about bullying developed in other national contexts and approached workplace bullying cross-culturally^{6, 9)}. This context is important because the prevalence of workplace mistreatment varies according to workers' perceptions¹⁰⁾ and their national culture⁴⁾.

Differences also exist in terms of the source of personal characteristics, such as gender and educational level. It is important to identify risk groups of workplace mistreatment in the context of future prevention. However, the results from empirical studies on sociodemographic factors and mistreatment are inconsistent. For example, among personal characteristics, gender has been the most widely studied. Some studies have reported more significant effects of mistreatment for women^{11, 12)}, while Hoel and Cooper found no significant gender differences in their UK-wide survey of bullying¹³⁾.

There has been substantial research on the health outcomes of workplace mistreatment. For example, several cross-sectional studies have found evidence of correlations between exposure to mistreatment and psychological, psychosomatic, and physical symptoms^{7, 14)}. Common symptoms reported by victims in different European countries include musculoskeletal complaints, anxiety, irritability, and depression^15–18). Two recent Norwegian longitudinal studies found that exposure to bullying behavior in the workplace predicts psychological distress two years later^{19, 20)}. In addition, social isolation, social maladjustment, low self-esteem, sleep problems, concentration difficulties, chronic fatigue, and burnout seem to be common symptoms in victims of workplace mistreatment³⁾. The international cost of outcomes related to work-place mistreatment is estimated to be between $17 and $36 billion annually²¹⁾, and an Australian study revealed that total national annual employer costs for lost productivity due to depression were estimated at AUD$8 billion per annum²²⁾.

To date, evidence has supported the hypothesis that workplace mistreatment has negative effects on employees' health. However, most of these studies have been based on Western samples. Although workplace mistreatment shares similar characteristics, other related research suggests that responses to workplace mistreatment may be different in Eastern countries²³⁾. Therefore, comparison between Western and Eastern countries has an important meaning when attempting to understand why workplace mistreatment will have stronger or weaker effects on health among workers with different cultural and personal backgrounds.

Given the negative personal and organizational effects of workplace mistreatment, every effort should be made to understand the mistreatment process and to prevent the consequent health outcomes. The aim of this study was to investigate whether workers' cultural and personal characteristics affect the relationship between workplace mistreatment and health problems. Gender and educational level were examined in both Korea and EU countries in order to understand the health effects of workplace mistreatment and identify groups at risk.

Subjects and Methods

We used data from the third Korean Working Condition Survey (KWCS) in 2011 and fifth European Working Condition Survey (EWCS) in 2010. These were nationally representative interview surveys and included questions relating to workers' socioeconomic data, workplace environment, and social and occupational health. Informed consent was obtained from all participants in both surveys, and detailed information about these surveys is available at the following websites: http://www.eurofound.europa.eu/working/surveys/ for the EWCS and http://www.kosha.or.kr/jsp/kwcs/ for the KWCS. The fifth EWCS comprises data from 35 European countries with 43,816 participants. The third KWCS, which was based on the EWCS, was conducted by the Korea Occupational Safety and Health Agency (KOSHA) in 2011. This survey recruited 50,032 participants by using stratified, multistage, random sampling of household units. For our analysis, we excluded self-employed participants (N=8,629 in the EWCS; 20,321 in the KWCS), those aged under 20 (N=722 in the EWCS; 317 in the KWCS), and participants who had missing data for some variables (N=1,329 in the EWCS); the final study sample included 33,136 participants for the EWCS and 29,404 participants for the KWCS.

Variables

Mistreatment

We defined the “Mistreatment” group as individuals to whom at least one of the following criteria applied: (1) discrimination, that is, being subjected to discrimination at work because of age, ethnicity, sex, nationality, or religion in the past 12 months; (2) violence, that is, being subjected to verbal abuse, unwanted sexual attention, threats and humiliating behavior, or physical violence during the course of work in the last month; and (3) bullying, that is, being subjected to bullying/harassment or sexual harassment during the course of work in the past 12 months.

General characteristics of the study subjects

The EWCS and KWCS surveys include questions about a wide array of characteristics; we chose to use age, sex, education level, household income level, employment status, gender composition in the workplace, and job classification. Education level was classified as “middle school or less” (for European countries, this is defined as “lower secondary or second stage of general education or less”), “high school” (European countries: “upper secondary education”), and “college or more” (European countries: “post-secondary non-tertiary education or more”). The gender composition in participants' workplace was ascertained by asking, “At your place of work, are workers with the same job title as you…?” with a choice of four answers: “mostly men”, “mostly women”, “more or less equal numbers of men and women”, and “nobody else has the same job title”. Jobs were classified into 10 groups according to the International Standard Classification of Occupation (ISCO) code: “legislators, senior officials and managers”, “professionals”, “technicians and associated professionals”, “clerks”, “service workers and shop and market sales workers”, “skilled agricultural and fishery workers”, “craft and related trades workers”, “plant and machine operators and assemblers”, “elementary occupations”, and “armed forces”.

Self-reported health problems

Self-reported health problems were assessed by the question, “Over the last 12 months, have you suffered from any health problems?” The KWCS and EWCS included 13 health-related questions relating to hearing problems, skin problems, backache, muscular pains in the shoulders/neck/upper limbs, muscular pains in lower limbs, headache/eyestrain, stomach ache, respiratory difficulties, cardiovascular disease, injuries, depression or anxiety, overall fatigue, and insomnia/general sleep difficulties. We excluded health problems caused by injury and grouped together the remaining 12 health problems into “somatising tendency”, “musculoskeletal pain”, “psychological symptoms”, and “overall fatigue”. The “somatising tendency” category comprised symptoms related to hearing problems, skin problems, stomach ache, respiratory difficulties, and headache/eyestrain²⁴⁾. “Musculoskeletal pain” grouped together muscular pains in the shoulders/neck/upper limbs and lower limbs and backache, and the “psychological symptoms” category referred to participants who experienced either depression or anxiety or insomnia/general sleep difficulties. The “overall fatigue” category was defined from only one health-related question, that referring to overall fatigue itself.

Mistreatment score and health outcome score

The Pressure-State-Response (PSR) model, which was pioneered by the Organisation for Economic Cooperation and Development (OECD), is a conceptual model of causality. It assumes that human activities exert pressures on the environment, thereby affecting environmental quality and the quantity of natural resources (“state”); society responds to these changes through environmental, general economic, and sectorial policies and through changes in awareness and behavior (“societal response”)²⁵⁾. We adapted the PSR model, defining mistreatment scores as “pressure”, calculated by the sum of experienced mistreatments in the workplace, including discrimination, violence, and bullying. We then transformed these scores using a scale of 0 to 10. That is, an individual with no experience of mistreatment would have a mistreatment score of 0, whereas an individual experiencing discrimination, violence, and bullying would score 10. In the same way, the health outcome score (considered the “state” aspect of the PSR model) was defined by the sum of the 12 self-reported health problems. The health outcome score was also transformed onto a scale of 0 to 10.

Statistical analysis

We analyzed the EWCS and KWCS data separately to compare European and Korean participants. General characteristics are presented as means and standard deviations for continuous variables and numbers and prevalences (%) for categorical variables. The mistreatment score and health outcome score means were calculated and plotted by nation, in order to look at national differences. To evaluate the associations between experience of mistreatment and each of the self-reported health problems, we performed logistic regression after adjusting for age, sex, and job classification; for the European data, we further adjusted for nation as well as these three variables. To compare health effects of workplace mistreatment between EU countries and Korea, effect modification was investigated by assessing the interaction term involving two data sets. We conducted additional analyses to evaluate gender and educational levels as modifying factors that might affect the relationship between workplace mistreatment and health outcomes. The stratified analysis was conducted using the variables of gender composition in the workplace, educational level, and estimated interaction terms. The statistical analysis was conducted using the SAS software (Version 9.22, SAS Institute, Cary, NC, USA).

Results

Table 1 shows participants' descriptive characteristics. There were 16,300 males and 16,836 females in the EWCS, among which 16.23% of males and 19.49% of females experienced some type of mistreatment. In the KWCS, there were 17,178 males and 12,226 females, and the prevalence of mistreatment was 14.07% for males and 15.57% for females. The mean age was similar for both survey samples. In the EWCS, the mean age was 41.41 (SD=11.52); for participants reporting mistreatment, it was 40.66 (SD=11.40). In the KWCS, the mean age was 41.75 (SD=11.76), while that for participants reporting mistreatment was 41.47 (SD=12.11). The Korean results show a trend for more educated participants to experience less mistreatment, but the trend was in the opposite direction for EU countries. Prevalence of mistreatment according to employment status and gender composition in the workplace was similar in both surveys, but the prevalence of mistreatment was greater overall for EWCS participants. Day laborers and individuals who worked mostly with women had a higher prevalence of mistreatment. Regarding job classification, mistreatment was higher in legislators, senior officials, and managers; professionals; and technicians and associated professionals in Europe than in Korea.

Table 1. Descriptive characteristics of the study population (N and %)

	European Working Condition Survey (EWCS)					Korean Working Condition Survey (KWCS)
	Total sample		Mistreatment		Prevalencec	Total sample		Mistreatment		Prevalencec
	N	%	N	%	%	N	%	N	%	%
Sex
Male	16,300	49.19	2,646	44.64	16.23	17,178	58.42	2,417	55.94	14.07
Female	16,836	50.81	3,281	55.36	19.49	12,226	41.58	1,904	44.06	15.57
Education level
Middle school	7,692	23.21	1,328	22.41	17.26	3,263	11.1	529	12.24	16.21
High school	13,483	40.69	2,281	38.48	16.92	11,394	38.75	1,740	40.27	15.27
University	11,961	36.1	2,318	39.11	19.38	14,747	50.15	2,052	47.49	13.91
Incomea
Lowest	3,852	16.29	529	12.11	13.73	3,558	12.1	503	11.65	14.14
Low-middle	8,721	36.88	1,477	33.81	16.94	11,745	39.95	1,948	45.11	16.59
High-middle	8,274	34.99	1,820	41.66	22.00	8,053	27.39	1,184	27.42	14.70
Highest	2,800	11.84	543	12.43	19.39	6,041	20.55	683	15.82	11.31
Employment statusb
Fixed	26,027	95.07	4,660	94.24	17.90	23,182	78.84	3,250	75.21	14.02
Temporary	1,270	4.64	267	5.4	21.02	4,353	14.8	678	15.69	15.58
Day laborer	80	0.29	18	0.36	22.50	1,869	6.36	393	9.1	21.03
Workplace gender composition
Mostly men	12,168	36.72	1,994	33.64	16.39	12,176	41.41	1,792	41.47	14.72
Mostly women	11,331	34.2	2,307	38.92	20.36	8,258	28.08	1,342	31.06	16.25
More or less equal numbers of men and women	6,706	20.24	1,214	20.48	18.10	7,565	25.73	1,020	23.61	13.48
Nobody else has the same job title	2,931	8.85	412	6.95	14.06	1,405	4.78	167	3.86	11.89
Job (ISCO code)
Legislators, senior officials, and managers	1,782	5.38	313	5.28	17.56	568	1.93	62	1.43	10.92
Professionals	5,227	15.77	962	16.23	18.40	5,031	17.11	664	15.37	13.20
Technicians and associated professionals	5,225	15.77	963	16.25	18.43	6,455	21.95	888	20.55	13.76
Clerks	3,968	11.97	657	11.08	16.56	2,959	10.06	466	10.78	15.75
Service workers and shop and market sales workers	6,013	18.15	1,372	23.15	22.82	3,669	12.48	532	12.31	14.50
Skilled agricultural and fishery workers	302	0.91	33	0.56	10.93	158	0.54	14	0.32	8.86
Craft and related trades workers	3,741	11.29	513	8.66	13.71	2,874	9.77	394	9.12	13.71
Plant and machine operators and assemblers	3,022	9.12	511	8.62	16.91	3,194	10.86	513	11.87	16.06
Elementary occupations	3,670	11.08	571	9.63	15.56	4,421	15.04	781	18.07	17.67
Armed forces	186	0.56	32	0.54	17.20	75	0.26	7	0.16	9.33
For total sample	33,136	100	5,927	100	17.89	29,404	100	4,321	100	14.70

^a  There was no information on income variables for 9,496 EWCS participants (1,561 participants affiliated with the mistreatment group).

^b  There was no information on income variables for 5,759 EWCS participants (982 participants affiliated with the mistreatment group).

^c  Prevalence of experiencing workplace mistreatment in past 12 months.

The mean mistreatment scores and health outcome scores (from the PSR model) differed by nation (Supplementary Table 1). Figure 1 shows the association between mistreatment score and health outcome score according to nation. The majority of countries in Europe reported more frequent mistreatment compared with Korea, and the health outcome score for Korea was the lowest of all the countries. Among European countries, Finland, Latvia, and Estonia showed the highest mistreatment and health outcomes, and Kosovo and Ireland had the lowest mistreatment and self-reported health problems, respectively.

Fig. 1.

Mean mistreatment and health outcome scores according to country.

The frequencies and associations between mistreatment and self-reported health problems for all participants and both of the respective surveys are shown in Table 2. There was a difference in the frequencies of health outcomes between the EWCS and KWCS. About half of the EWCS participants reported somatizing tendency, musculoskeletal pain, and overall fatigue, whereas the frequencies of these health outcomes in the KWCS were from 19.84 to 38.66%: the differences in frequencies between the EWCS and KWCS were about 20%. All health outcomes were significantly associated with mistreatment in both surveys, but how closely workplace mistreatment was associated with health outcomes was somewhat different in the two surveys. Psychological symptoms had the strongest association with mistreatment compared with other variables, and this association was stronger for KWCS participants (OR=3.400, 95% CI=2.955–3.912) than EWCS participants (OR=2.643, 95% CI=2.490–2.806). Somatizing tendency and musculoskeletal pain also showed a stronger association with mistreatment for Korean participants than for European participants, and all health outcomes except overall fatigue showed statistically significant interaction terms between in the two surveys. That is, significant health outcomes were observed among participants who experienced mistreatment in their workplace in both surveys; however, the risk elevations were greater in the KWCS than in the EWCS.

Table 2. Mistreatment frequency and multiple logistic regression analysis^b results for the association between mistreatment and self-reported symptoms (OR=odds ratio; 95% CI=95% confidence intervals)

Self-reported symptoms	Total		European Working Condition Survey (EWCS)b		Korean Working Condition Survey (KWCS)		p-interaction
	N (%)	OR (95% CI)	N (%)	OR (95% CI)	N (%)	OR (95% CI)
Somatizing tendency	22,746 (36.37)	2.307 (2.209–2.409)	16,912 (51.04)	2.126 (2.003–2.256)	5,834 (19.84)	2.722(2.536–2.921)	<0.0001
Musculoskeletal pain	31,631 (50.58)	2.165 (2.069–2.265)	20,263 (61.15)	2.004 (1.880–2.135)	11,368 (38.66)	2.268 (2.120–2.426)	0.005
Psychological symptoms	9,398 (15.03)	2.640 (2.509–2.778)	8,485 (25.61)	2.643 (2.490–2.806)	913 (3.11)	3.400 (2.955–3.912)	0.0012
Overall fatigue	20,727 (33.14)	1.952 (1.869–2.039)	13,733 (41.44)	1.925 (1.818–2.038)	6,994 (23.79)	1.895 (1.767–2.032)	0.5483

^a  The logistic regression model was adjusted for age, sex, and job classification.

^b  The EWCS data was adjusted for nations.

Table 3 shows the factors affecting self-reported health problems among those who experienced any type of mistreatment. Overall, workplace mistreatment was most closely associated with psychological symptoms, but the effect size of workplace mistreatment was different according to gender composition and educational level. In the EWCS, there were no significant effect differences across gender composition in the workplace among females; however, male subjects who worked with mostly men were more likely to report musculoskeletal pain (OR=2.244), and those who performed unique jobs (“nobody else has the same job title”) suffered more from psychological problems (OR=3.984) when they experienced mistreatment at work. There was little difference in the ORs of health problems according to education level.

Table 3. Odd ratios of mistreatment for self-reported health problems according to workplace gender composition and educational levels (EWCS=European Working Condition Survey; KWCS=Korean Working Condition Survey)

	EWCS				KWCS
	Somatizing tendency	Musculoskeletal pain	Psychological symptoms	Overall fatigue	Somatizing tendency	Musculoskeletal pain	Psychological symptoms	Overall fatigue
Sex
Male	2.180	2.003	2.956	2.336	2.705	2.289	3.316	1.86
Mostly men	2.224	2.244	2.943	2.394	2.713	2.319	3.862	2.060
Mostly women	2.575	1.633	2.858	2.857	3.633	2.129	2.941	1.607
More or less equal numbers of men and women	2.029	1.758	2.909	2.059	2.457	2.249	2.189	1.503
Nobody else has the same job title	1.877	1.704	3.984	2.406	2.306	2.493	2.579*	1.354*
p-interactiona	0.4636*	0.0309	0.5226*	0.5389*	0.4992*	0.8954*	0.0265	0.0016
Female	2.161	2.020	2.530	2.270	2.839	2.300	3.642	1.965
Mostly men	1.756	1.903	2.351	1.919	3.179	2.509	6.772	2.352
Mostly women	2.298	2.238	2.582	2.327	2.903	2.089	3.317	1.997
More or less equal numbers of men and women	2.151	1.755	2.618	2.225	2.698	2.576	3.286	1.643
Nobody else has the same job title	2.098	1.848	2.452	2.720	2.097	3.111	6.631	2.497
p-interactiona	0.5285*	0.1012*	0.6269*	0.3282*	0.1112*	0.259*	0.6659*	0.4092*
Education level
Middle school	2.225	1.863	2.695	2.284	1.543	1.989	2.355	1.504
High school	2.274	2.295	2.870	2.349	3.356	1.937	3.218	1.781
University	2.024	1.851	2.558	2.241	2.738	2.716	4.016	2.15
p-interactionb	0.1839*	0.5807*	0.7967*	0.5521*	0.015	<0.0001	0.021	0.0003

^a  Interaction between mistreatment and workplace gender dominancy.

^b  Interaction between mistreatment and educational level.

*  Not significant.

The Korean data show different patterns. Male KWCS participants who worked mostly with men reported more frequent psychological symptoms and overall fatigue when they experienced mistreatment (OR for psychological symptoms=3.862, OR for overall fatigue=2.060). On the other hand, men who worked with mostly women showed a greater risk of somatizing tendency due to workplace mistreatment (OR=3.633). In female KWCS participants, workers who worked alone (“nobody else has the same job title”) showed a strong association between mistreatment and health outcomes, especially psychological symptoms (OR=6.631). The OR of all females for musculoskeletal pain was 2.300, while that of females who worked alone was 3.111. For these two groups of females, the ORs of psychological symptoms were 3.642 and 6.631, respectively. On the other hand, females who worked with mostly men showed a more increased risk of somatizing tendency and psychological symptoms related to workplace mistreatment (OR for somatizing tendency=3.633, OR for psychological symptoms=6.772).

Education level also modifies the relationship between workplace mistreatment and health problems in Korea in contrast with EU countries. Individuals with a higher level of education were more likely to report health problems when they experienced mistreatment, especially psychological symptoms (OR=4.016). Furthermore, all health outcomes in Korea showed a significant interaction between mistreatment and educational level; this was not the case for any health outcome in European countries.

Discussion

Our aim in this study was to investigate effects of workers' cultural and personal characteristics on the relationship between workplace mistreatment and health problems, exploring cultural areas, gender and educational levels as modifying variables in these relationships. Generally speaking, the prevalence of workplace mistreatment and health problems was higher in EU countries than in Korea. However, the association between workplace mistreatment and health problems was stronger in Korea than in EU countries, and the pattern of these associations varied depending on gender, gender composition in the workplace, and educational level. The results of our study support the hypothesis that certain kinds of individual characteristics and cultural factors may exacerbate the damaging effects of workplace mistreatment, especially in Korea.

The survey data indicated that 17.89% of workers in EU countries and 14.7% of workers in Korea experienced some kind of mistreatment, such as workplace violence, bullying, and harassment, over the last year. Previous studies have revealed that approximately 4–10% of the working population in Europe has been exposed to workplace mistreatment³⁾. Although the prevalence of workplace mistreatment is different by method and sampling technique, it is obvious that workplace mistreatment is reaching epidemic levels, and the World Health Organization has declared this phenomenon a significant public health threat²⁶⁾. One of the advantages in our study is that we used the same questionnaires to survey two different samples, because the KWCS was based on the EWCS. Therefore, even if the perception of workplace mistreatment varies according to the workers' national culture, comparison of two samples is possible and worthwhile. The antecedents and consequences of workplace mistreatment have received much attention in psychology and occupational medicine^{1, 4, 7)}, but cross-cultural examinations of workplace mistreatment have been rare^{6, 9)}. Some studies have investigated differences in the way that employees conceptualize workplace mistreatment²⁷⁾. In our study, all health outcomes were significantly associated with mistreatment in both surveys, but how closely related workplace mistreatment and health outcome were differed somewhat between the EU countries and Korea. Three categories of health outcome showed a stronger association with mistreatment among Korean participants than among European participants. Evidence suggests that cultural beliefs and values may mutually influence how individuals perceive and respond to aggressive acts¹²⁾. For example, Salin (2003) argues that workplace mistreatment is perceived as a “normal” and acceptable way of getting things done in some cultures, while in others it is viewed as unacceptable. Northern European countries, the UK, and Australia, which are characterized by negative attitudes towards signs of abuse of power, low power distance, more feminine values, and individualism, tend to have a lower threshold for categorizing inadequate behaviors as mistreatment and may be more ready to use the right to complain about it⁹⁾. The results of our PSR model showed that in European countries, both mistreatment and response scores were higher than in Korea (Fig. 1). Drawing on power distance research, we supposed that while workplace mistreatment is universally perceived as a negative situation, its effects will differ from low power-distance cultures (EU countries) to high power-distance cultures (Eastern Asian countries). This suggests that mistreatment may be tolerated to some extent by employees in cultures that accept a hierarchically based power disparity.

The main factor linking exposure to workplace mistreatment and health outcomes is stress: Workplace mistreatment can be considered a major job stress factor. Once workplace mistreatment is perceived as a traumatic event, cognitive processes produce changes in the victim's thoughts and beliefs²⁸⁾. According to the social cognition view, individuals hold certain assumptions or schemas regarding the world and the self, which are stable and generally positive²⁹⁾. A traumatic event presents information that is incompatible with pre-existing schemas regarding personal invulnerability, generosity of the world, meaning, self-worth, and relations with others³⁰⁾. Eventually, an adverse emotional reaction develops.

There is now substantial evidence linking work characteristics, including workplace mistreatment, to the prevalence of work-related health problems^{2, 4)}. Given the complexity and variability of stressful experience at work, it is essential to identify its harmful components with the help of theoretical models. The aim of work stress models is to understand how stress influences the pathogenesis of disease in work life. Two such models in this area have received special attention: the effort-reward imbalance (ERI) model and cognitive activation theory of stress (CATS) model.

Siegrist's ERI model proposes that health risks derive from the mismatch between high efforts at work and low rewards received³¹⁾. This model focuses on the reciprocity of exchange in occupational life, where high-cost/low-gain conditions are considered particularly stressful. Work effort is part of a social contract, which operates with three types of reward: money, esteem, and career opportunities, including job security. Among these rewards, workplace mistreatment could be interpreted as a low level of social approval, inducing lack of esteem. Lack of esteem and approval, despite high effort, may produce emotional distress. The imbalance between high efforts and low rewards elicits recurrent feelings of threat, anger, and depression or demoralization, which in turn evoke sustained autonomic arousal. The Whitehall II study findings showed that ERI predicts the incidence of self-reported coronary heart disease (CHD)³²⁾, psychiatric disorder³³⁾, and poor health functioning³⁴⁾ during follow-up.

A complementary concept, CATS, proposes that a stress response occurs when an individual perceives a discrepancy between what should be and what is—between the set value and the real value. The core assumption of the CATS model is that sustained or chronic arousal produced by stress, such as worry or rumination, may produce physiological activation and lead to health impairment. Eventually, an adverse stress reaction develops, which is characterized by physiological arousal (e.g. increased heart rate or blood pressure). Thus, the increase in arousal as a response to stressful situations such as mistreatment at work may lead to the development of health problems³⁵⁾.

Workplace mistreatment may contribute to health disparities by having differential effects on minor groups compared with dominant groups. For example, one study examined the relationship between the incidence of workplace bullying and everyday experiences of members of ethnic and racial minorities in the American workplace and found that, even though experiences of workplace mistreatment were significantly associated with negative emotional reactions for all targets, African-American and Hispanic/Latino workers who were targets of general bullying were more likely to respond actively than white workers³⁶⁾. A prospective cohort study of working women in the United States indicated that women exposed to low social support at work are at significantly higher risk of poor functional status and a decline in mental health over time³⁷⁾. The results of the current study also highlighted a difference in the perception of workplace mistreatment and health complaints between minor and dominant groups (Supplementary Table 2). Participants who worked with different gender co-workers showed a relatively higher risk of health symptoms due to workplace mistreatment, particularly female workers in Korea (Table 3).

We found an overall stronger relationship between workplace mistreatment and health problems for female workers than for male workers in Korea (Table 3). Various studies have suggested the importance of gender in the mistreatment process^{11, 12)}, with results indicating that the effects of mistreatment tend to be greater in women. Gender differences in workplace mistreatment can by explained in part by the tendency of women to experience traumatic events that differ fundamentally from those experienced by males³⁸⁾. Additionally, there is strong evidence of a sex-related hemispheric lateralization of amygdala function in memory of a traumatic experience, especially in the processing of strong emotional memories³⁹⁾. Similarly, another study revealed that post-traumatic symptoms were more prevalent among women (49%) than men (35.3%) when exposed to workplace mistreatment¹¹⁾. On the basis of these findings, it has been suggested that gender differences in the cognitive appraisal of traumatic stressors are an important issue in explaining female-male differences, as well as gender-specific acute psychobiological reactions to trauma⁴⁰⁾.

It is also noteworthy that educated workers in Korea have a greater risk of health problems related to workplace mistreatment, but this is somewhat difficult to interpret. When more educated Korean people experience mistreatment or harassment in the workplace, they more frequently they tend to report health problems. This effect of educational level is not apparent for European participants. There may be cultural reasons for this difference between Korea and European countries. One possible explanation is that subjective social class identification is closely connected with educational level in Korea. There is a widespread belief among Koreans that higher social status can be obtained as a result of educational achievement⁴¹⁾. Therefore, higher educational level is equated with higher social class. Moreover, the general trend of change has been increasing job insecurity for white-collar workers in Korea and an intensification of educational pursuits⁴²⁾, which is an expression of high effort. If someone with a higher educational level experiences mistreatment at work, they are more likely to regard that event as distressing and unacceptable than a worker with a lower educational level. Workplace mistreatment being regarded as low reward, despite high effort to gain high educational level, may produce emotional distress. The imbalance between high efforts and low rewards would elicit psychological stress, which in turn would evoke somatic symptoms.

The current study has several methodological shortcomings. First, the cross-sectional design of this study did not allow us to assume a causal relationship between individual characteristics and the health effects of workplace mistreatment. There is a probability that health problems lead to mistreatment. Hence, the potential for overestimation or underestimation of risk remains. Second, our study was based on self-reported health problems, with no clinical diagnosis. However, we believe that self-reported assessment of work stress is not a source of major bias in our study. Third, the different types of workplace mistreatment, such as discrimination, harassment, and violence, were assessed by a simple set of questionnaires that lacked highly structured questions or clear definitions. Forth, this study considered the country as representing the culture, but there are many other cultural determinants in addition to country that should be considered, such as language, proximity and topography, religion, economic development, technological development, political boundaries, industry type, and climate. Although we adapted the PSR model to compare overall workplace mistreatment and health outcome according to nation, considering nations, which are heterogeneous in the EU, as representing cultures would be inadequate.

Notwithstanding these limitations, our sample included a very large number of employees from the general working population, allowing us to study a nonselective population, as well as men and women separately, which has been shown to be crucial. Moreover, as we compared representative data from Korea and EU countries, surveyed using almost identical methodologies and survey questionnaires, it was possible to conduct in-depth comparison analyses.

In conclusion, workplace mistreatment is closely associated with physical and mental health problems, especially among workers with higher educational levels and females who work alone in Korea. Awareness of these gender and educational differences is an important step in targeting preventive measures and improving their efficiency. Special attention should be paid to these potentially vulnerable groups in designing strategies to reduce health complaints due to workplace mistreatment.

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