The correlation among occupational stress, coping style and depressive symptoms in 2,083 Chinese manufacturing workers

doi:10.21203/rs.3.rs-4341843/v1

Background

This study aims to investigate the correlation among occupational stress, coping style and depressive symptoms in manufacturing workers of China.

Methods

A total of 2,083 workers from two manufacturing enterprises in Beijing City and four manufacturing enterprises in Guangdong Province are selected as study subjects using judgment sampling method. The occupational stress, coping style, and depression symptoms are accessed using the Core Occupational Stress Measurement Scale, Trait Coping Style Questionnaire and Patient Health Questionnaire Depression Scale, and we analyze the correlation among occupational stress, coping style and depressive symptoms.

Results

A total of 2,311 questionnaires are distributed, and 2,083 valid questionnaires are collected, with a valid questionnaire recovery rate of 90.1%. The average scores of occupational stress, positive coping style, negative coping style and depressive symptoms among the study subjects are 45.2, 31.7, 23.7 and 6.3, respectively. The detection rates of occupational stress and depressive symptoms are 29.5% (615/2,083) and 15.7% (327/2,083). Depressive symptoms are positively correlated with occupational stress and negative coping style (both P < 0.001), and negatively correlated with positive coping style (P < 0.001). Occupational stress is positively correlated with negative coping style (P < 0.001) and negatively correlated with positive coping style (P < 0.001). The four dimensions of occupational stress explained 15.7% of variation in depressive symptoms (P < 0.001). The inclusion of the two dimensions of coping style on the above basis can explain 19.5% of the variation in depressive symptoms (P < 0.001). Meanwhile, the four dimensions of occupational stress has a statistically significant effect on depressive symptoms (P < 0.05).

Conclusions

Occupational stress can directly affect the occurrence of depressive symptoms in manufacturing workers of China. Coping style moderates the effect of occupational stress on depressive symptoms. Positive coping style can help alleviate the adverse effects of occupational stress and reduce the risk of depressive symptoms.

Biological sciences/Psychology

Health sciences/Health occupations

Manufacturing

Workers

Occupational stress

Coping style

Depression symptoms

Correlation

Influencing

Manufacturing is the main body of China's national economy and has played a major role in China's economic development [1]. With the gradual deepening of economic globalization and China's industrial structure adjustment, manufacturing enterprises are fiercely competitive, and they are still facing problems such as industrial basic capabilities and competitiveness to be improved [2, 3]. Affected by the characteristics of its industry, manufacturing workers have been carrying out repetitive, monotonous and fast-paced operations for a long time, long working hours and maintaining the same working posture, dense assembly lines, crowded working space, etc., resulting in various physical and mental health problems of workers, which in turn lead to absenteeism, production accidents and reduced working capacity, bringing heavy economic burden to enterprises and society [4, 5]. The construction of a manufacturing power has also put forward higher skill requirements for front-line workers in the manufacturing industry [6]. Research results have shown that manufacturing workers are at high risk of mental illnesses such as occupational stress and depression symptoms [7]. Depressive symptoms are a negative psychological state that is clinically defined as depression when depression symptoms reach a certain level of severity, persist for an extended period of time, and cause severe psychological damage to an individual [8]. The occurrence of depressive symptoms is related to a variety of factors, including work-related factors, individual, social, or economic problems [9]. Research results have shown a positive correlation between working hours and depressive symptoms [10], and that people who receive work-related social support are less likely to experience depression [11, 12], and depressive symptoms are a risk factor for retirement [13].

Occupational stress, also known as work stress and work pressure, referring to the physical and psychological reactions that occur when the requirements of an individual's job position do not match the individual's abilities, resources, or needs, and if persistent, can lead to physical and mental health impairment [14]. According to the World Health Organization, occupational stress has become a worldwide epidemic, and labor losses caused by occupational stress has become among the top 10 in the burden of occupation-related diseases. Depressive symptoms are negative emotional experiences, persistent and severe depressive symptoms can lead to impaired social ability, depressive symptoms in the workplace will not only have a serious negative impact on employees' psychology and behavior, but also lead to economic losses such as reduced productivity, absenteeism, and personnel turnover [15, 16]. China's occupational population lacks early identification methods for occupational psychological disorders at present, and the proportion of patients receiving early and effective intervention or even visiting medical and health institutions is very small. Cross-sectional and cohort studies of occupational population has found that occupational stress is closely associated with the occurrence of depressive symptoms [17, 18]. Occupational populations with depressive symptoms may develop more serious psychological or mental illnesses if combined with negative emotions such as occupational stress [19]. Trait coping styles are the attitudes and behavioral traits that individuals exhibit when they encounter difficulties or setbacks [20], and the two dimensions of negative and positive coping styles may play a mediating role in the psychological states of the study subjects [21]. Negative coping style has been found to have a partial mediating effect on nurses' occupational stress and fatigue [22]. In addition, it has been shown that trait coping style plays a parallel and multiple mediating role between positive psychological qualities and depressive symptoms in recruits [23]. However, there is little research on whether trait coping style plays a mediating effect on the relationship between occupational stress and depressive symptoms in manufacturing workers.

Most workers′ occupational careers account for more than half of their life cycle, and only when the health of manufacturing workers is guaranteed we can provide solid guarantee and support for the vigorous development of China's manufacturing industry [24]. Therefore, this study aims to understand the mental health of manufacturing workers and investigate the correlation among occupational stress, coping style and depressive symptoms. The clarification of this relationship is conducive to the implementation of psychological interventions for manufacturing workers of China, which is of great significance for promoting the physical and mental health of this population, ensuring the efficiency of China's manufacturing industry, and promoting sustainable and healthy economic development.

Study design and population

This study adopts a cross-sectional design, which is undertaken by National Institute of Occupational Health and Poison Control of Chinese Center for Disease Control and Prevention, and jointly completes by multiple provincial cooperation units. According to the manufacturing development cluster, combined with the degree of enterprise cooperation, the workers from two manufacturing enterprises in Beijing City and four manufacturing enterprises in Guangdong Province are selected as the research subjects from June to October 2020 using the judgment sampling method. Inclusion criteria: i) Aged more than 18 years old. ii) Working in the position for continuous half a year or more. iii) The questionnaire information is complete. Exclusion criteria: i) long-term sick leave. ii) Have a history of mental illness, or have taken psychotropic drugs during one week before the investigation.

Ethics approval and consent to participate

This study is reviewed and approved by the National Institute of Occupational Health and Poison Control of Chinese Center for Disease Control and Prevention (No. NIOHP201914), and all participants sign informed consent forms.

Basic information

The Basic Situation Questionnaire designed by our research group is used to investigate the basic situation of the research subjects, including sociodemographic characteristics (gender, age, education level, marital status, personal monthly income) and job characteristics (length of service, average weekly working hours, job position and shift work of the post).

Occupational stress

The Core Scale of Occupational Tension Measurement developed by our research group is used to evaluate the occupational stress status of the research subjects [25]. The scale includes four dimensions: social support, organization and reward, demand and effort, and autonomy, with 5, 6, 4 and 2 questions, respectively. A Likert 5-point score is used, ranging from 1 point indicating "strongly disagreeing" and 5 points indicating "strongly agreeing". The total score of occupational stress is calculated according to the formula "occupational stress score=(6－social support dimension score)＋organization and reward dimension score＋demand and effort dimension score＋(6－autonomy dimension score)". The total score ranges from 17 to 85 points, and a higher total score indicates a more severe degree of occupational stress [26]. The higher the score of social support and autonomy, the less social support and autonomy they received at work. The higher the score of the organization and reward, demand and effort dimension, the more effort is given at work, and the less reward is received. The total score≥50.0 points is judged to be the existence of occupational stress. In this study, the cumulative variance contribution rate of the common factor is 62.1%, the goodness-of-fit index (GFI), comparative fit index (CFI) and root mean square error of approximation (RMSEA) are 0.904, 0.912 and 0.079, respectively, and the Cronbach′s α coefficients of the aggregate table and four dimensions are 0.794, 0.906, 0.787, 0.719 and 0.808, respectively [25]. The results show that the scale has good reliability and validity, and can be used as a measurement and evaluation tool for the occupational tension of manufacturing workers in China.

Coping style

The Trait Coping Style Questionnaire (TCSQ) is used to evaluate the individual's relatively stable coping style with certain personality tendencies to different events in life [27]. The scale includes two dimensions, positive coping style and negative coping style, with 10 items in each dimension. Among them, the positive coping items include items of 1, 3, 5, 8, 9, 11, 14, 15, 18 and 20, and the negative coping items include items of 2, 4, 6, 7, 10, 12, 13, 16, 17 and 19. A Likert 5-point score is used, ranging from 1 point indicating "definitely not" and 5 points indicating "definitely yes". The total score of the response method is the cumulative score of each dimension of the question. Among them, the total score of the positive coping style dimension ranged from 10 to 50 points, and the higher the total score, the higher the degree of active coping. The total score of the negative coping style dimension ranges from 10 to 50 points, and the higher the total score, the higher the degree of negative coping [28]. The Cronbach′s α coefficients of the total scale and the two dimensions are 0.861, 0.878 and 0.889, respectively. The results show that the scale has good reliability and validity, and could be used as a measurement and evaluation tool for the coping style of manufacturing workers in China.

Depressive symptoms

The Chinese edition of the Patient Health Questionnaire Depression Scale (PHQ-9) is used to evaluate the depressive symptoms of the study subjects [29]. This scale is a simple and effective tool for diagnosing and assessing the severity of depression [30]. The scale includes nine items. We use a Likert 4-point score, based on the frequency of symptoms over the past two weeks, with 0 point indicating "not at all" and 3 points indicating "always". The score ranges from 0 to 27 points, and the higher the score, the more severe the depressive symptoms [31]. The score of ≥10 points is judged to be the presence of depressive symptoms. The Cronbach's α coefficient on the scale in this study is 0.913, indicating that the scale has good reliability.

Quality control

The research group formulates a unified quality control plan, and clarifies the responsibilities at all levels, including: i) Pre-investigation: The leader of the research group communicates with the surveyed enterprise, clarifies the purpose and significance of the investigation, and obtains the support of the enterprise leaders to ensure the smooth progress of the investigation. We uniformly train investigators on project design plans, precautions for filling in questionnaires, on-site investigation skills, etc. ii) Mid-investigation: While distributing questionnaires on site, the investigators are responsible for explaining to the research subjects the purpose of the survey and the precautions for filling out the questionnaire. The study subjects fill in the questionnaire in the form of anonymous self-filling questionnaires which are collected on the spot. We establish a questionnaire review system for investigators, quality controllers and investigation leaders, and conducted secondary investigations for unqualified questionnaires. iii) Post-survey: the collected questionnaires are examined the internal logic between variables and questionnaires with a missing degree of more than 10.0% are excluded. The questionnaire adopts EpiData 3.1 software for double data entry, and strives for good data quality. We also standardize the source control of missing data during data cleaning, and the processing of missing data (filling or deletion).

Statistical analysis

All statistical tests are bilateral (α=0.05). Counting data is expressed in frequency (n) and composition ratio (%). If the measurement data follow a normal distribution by the normality test, they are described by mean±standard deviation. The two-independent samples t-test is used for the comparison of means between the two groups, and the one-way ANOVA is used for the comparison of the means between multiple groups. If they don’t follow a normal distribution after the normality test, the measurement data are described by the median (M) and the 25^th and 75^th percentiles (P₂₅, P₇₅). Pearson correlation analysis is used to analyze the correlation among occupational stress, coping style and depressive symptoms. Stratified regression analysis is used to analyze the correlation among occupational stress, coping style and depressive symptoms (forced entry method). Taking the depressive symptom score as the dependent variable, the demographic characteristic variable is introduced as the control variable in the first layer. The second layer introduces four dimensional variables of occupational tension, namely social support, organization and return, demand and giving, and autonomy. The third layer introduces two dimensional variables of coping style, namely positive coping style and negative coping style. We assess the extent to which the dimensions of occupational stress and coping style are associated with depressive symptoms. All data are statistically analyzed using SPSS 21.0 software.

Basic information

A total of 2,311 questionnaires are distributed and 2,083 valid questionnaires are recovered, with a recovery rate of 90.1%. The age of the study subjects is 19-60 (35±8) years, and the length of service in this position is 4.1 (2.3, 8.5) years. Among them, 54.3% are men and 45.7% are women. The majority of them are 31-40 years old, accounting for 40.1%. High school or technical secondary school education is the majority, accounting for 47.0%. Married cohabitation is the majority, accounting for 64.5%. The monthly income of individuals is mainly 3,000-<5,000 yuan, accounting for 41.8%. The majority of the working years in this position are 2.0-<5.0 years, accounting for 38.0%. The average weekly working hours were mostly 41-48 h, accounting for 26.4%. Assembly line work is the mainstay, accounting for 63.5%. The working system is mostly daytime shifts, accounting for 76.9%.

Comparison of occupational stress, coping style and depression symptom scores

The total scores of occupational stress is 45.2±7.8, and the scores of social support, organization and reward, demand and effort, and autonomy are 19.4±3.6, 15.4±4.4, 12.1±3.0 and 4.9±1.9, respectively, and the detection rate of occupational stress is 29.5% (615/2,083). The scores of positive coping style and negative coping style are 31.7±7.1 and 23.7±7.1, respectively. The depressive symptom score is 6.3±4.6, and the detection rate of depressive symptoms is 15.7% (327/2,083). The scores of occupational stress, coping style and depressive symptoms in different demographic groups are shown in Table 1, 2 and 3.

Table 1 Comparison among the scores of occupational stress in different demographic groups

Groups		Total N(%)	Occupational stress score (Mean±SE)	p value
Total		2083(100.0)	45.2±7.8
Gender	Male	1131(54.3)	45.2±8.1	0.759
	Female	952(45.7)	45.1±7.5
Age	19-25	294(14.1)	45.5±8.3	0.088
	26-30	446(21.4)	44.4±8.0
	31-40	836(40.1)	45.2±8.0
	41-50	419(20.1)	45.5±7.0
	51-60	88(4.2)	46.2±6.9
Education level	Junior high school and below	854(41.0)	45.8±7.1	0.005
	High school/Technical secondary school	980(47.0)	44.6±8.3
	College degree and above	249(12.0)	45.2±8.1
Marital status	Unmarried/Divorced/Widowed	537(25.8)	45.3±8.2	0.489
	Married cohabitation	1344(64.5)	45.1±7.7
	Married separation	202(9.7)	45.8±7.7
Personal monthly income (¥)	＜3000	301(14.5)	45.5±7.3	＜0.001
	3000-＜5000	871(41.8)	45.6±7.9
	5000-＜7000	664(31.9)	45.6±7.4
	≥7000	247(11.8)	42.4±8.6
Length of service (years)	0.5-＜2.0	364(17.5)	44.9±7.8	0.183
	2.0-＜5.0	792(38.0)	45.7±7.7
	5.0-＜10.0	492(23.6)	45.0±7.9
	10.0-35.7	435(20.9)	44.8±7.8
Average weekly working hours	≤40	198(9.5)	44.1±7.7	0.008
	41-48	549(26.4)	45.2±7.7
	49-58	451(21.6)	44.5±8.1
	59-66	521(25.0)	45.4±7.3
	≥67	364(17.5)	46.2±8.3
Job position	Assembly line	1322(63.5)	46.1±7.5	＜0.001
	Non-assembly line	761(36.5)	43.6±8.1
Shift work	No	1602(76.9)	45.3±7.4	0.415
	Yes	481(23.1)	44.9±9.0

Table 2 Comparison among the scores of coping style in different demographic groups

Groups		Total N(%)	Positive coping style score (Mean±SE)	p value	Negative coping style score (Mean±SE)	p value
Total		2083(100.0)	31.7±7.1		23.7±7.1
Gender	Male	1131(54.3)	31.7±7.0	0.833	23.8±7.1	0.265
	Female	952(45.7)	31.7±7.3		23.5±7.1
Age	19-25	294(14.1)	31.7±6.7	0.571	24.2±7.6	0.064
	26-30	446(21.4)	31.6±6.9		23.7±6.8
	31-40	836(40.1)	31.5±7.1		24.0±7.2
	41-50	419(20.1)	32.1±7.8		22.8±7.0
	51-60	88(4.2)	32.4±6.6		23.4±6.8
Education level	Junior high school and below	854(41.0)	31.6±7.2	0.323	23.5±7.1	0.511
	High school/Technical secondary school	980(47.0)	31.9±7.0		23.9±7.1
	College degree and above	249(12.0)	31.3±7.1		23.4±7.2
Marital status	Unmarried/Divorced/Widowed	537(25.8)	31.1±7.2	0.083	24.3±7.6	0.007
	Married cohabitation	1344(64.5)	31.8±7.3		23.3±7.0
	Married separation	202(9.7)	32.2±6.0		24.4±6.2
Personal monthly income (¥)	＜3000	301(14.5)	31.4±7.4	0.466	23.1±7.2	0.333
	3000-＜5000	871(41.8)	31.6±7.2		23.9±7.4
	5000-＜7000	664(31.9)	31.7±7.1		23.6±7.0
	≥7000	247(11.8)	32.3±6.7		23.9±6.4
Length of service (years)	0.5-＜2.0	364(17.5)	31.7±7.0	0.065	23.2±7.1	0.479
	2.0-＜5.0	792(38.0)	31.5±7.2		23.6±7.2
	5.0-＜10.0	492(23.6)	31.3±6.9		23.9±7.0
	10.0-35.7	435(20.9)	32.5±7.3		23.8±7.2
Average weekly working hours	≤40	198(9.5)	31.7±7.5	0.961	22.8±7.5	0.021
	41-48	549(26.4)	31.6±7.4		23.6±7.5
	49-58	451(21.6)	31.7±7.2		23.6±6.9
	59-66	521(25.0)	31.9±7.3		23.4±6.9
	≥67	364(17.5)	31.6±6.2		24.7±6.9
Job position	Assembly line	1322(63.5)	31.5±7.3	0.111	23.6±7.1	0.318
	Non-assembly line	761(36.5)	32.0±6.9		23.9±7.2
Shift work	No	1602(76.9)	31.5±7.3	0.044	23.4±7.2	0.002
	Yes	481(23.1)	32.3±6.6		24.5±6.9

Table 3 Comparison among the scores of depressive symptoms in different demographic groups

Groups		Total N(%)	Depression symptoms score (Mean±SE)	p value
Total		2083(100.0)	6.3±4.6
Gender	Male	1131(54.3)	6.4±4.6	0.061
	Female	952(45.7)	6.1±4.6
Age	19-25	294(14.1)	6.8±4.9	0.088
	26-30	446(21.4)	6.5±4.6
	31-40	836(40.1)	6.3±4.7
	41-50	419(20.1)	5.5±4.3
	51-60	88(4.2)	6.1±4.7
Education level	Junior high school and below	854(41.0)	6.0±4.6	0.005
	High school/Technical secondary school	980(47.0)	6.4±4.6
	College degree and above	249(12.0)	6.5±4.6
Marital status	Unmarried/Divorced/Widowed	537(25.8)	6.8±4.8	0.489
	Married cohabitation	1344(64.5)	6.1±4.6
	Married separation	202(9.7)	6.3±4.5
Personal monthly income (¥)	＜3000	301(14.5)	6.0±4.8	＜0.001
	3000-＜5000	871(41.8)	6.3±4.8
	5000-＜7000	664(31.9)	6.1±4.4
	≥7000	247(11.8)	6.8±4.3
Length of service (years)	0.5-＜2.0	364(17.5)	6.2±4.4	0.183
	2.0-＜5.0	792(38.0)	6.4±4.7
	5.0-＜10.0	492(23.6)	6.2±4.6
	10.0-35.7	435(20.9)	6.1±4.8
Average weekly working hours	≤40	198(9.5)	5.8±4.7	0.008
	41-48	549(26.4)	6.1±4.8
	49-58	451(21.6)	6.4±4.7
	59-66	521(25.0)	6.0±4.3
	≥67	364(17.5)	6.9±4.7
Job position	Assembly line	1322(63.5)	6.2±4.6	0.209
	Non-assembly line	761(36.5)	6.4±4.7
Shift work	No	1602(76.9)	6.1±4.6	＜0.001
	Yes	481(23.1)	6.9±4.8

Correlation analysis among occupational stress, coping style and depressive symptoms

Depressive symptoms are positively correlated with occupational stress and negative coping style (r are 0.388 and 0.530, respectively, and both P<0.001), negatively correlated with positive coping style (r is －0.142, P<0.001). Occupational stress is positively correlated with negative coping style (r is 0.331, P<0.001), and negatively correlated with positive coping style (r is －0.259, P<0.001). Among them, depressive symptoms are positively correlated with the organizational and reward, demand and effort dimensions of occupational stress and negative coping style (r are 0.285, 0.269 and 0.530, respectively, and all P<0.001), and negatively correlated with the social support dimensions of occupational stress and positive coping style (r are －0.256 and －0.142, respectively, and both P<0.001). Positive coping style is positively correlated with social support and autonomy of occupational stress (r are 0.277 and 0.057, respectively, and both P<0.05), and negatively correlated with the dimensions of organization and reward, demand and effort of occupational stress (r are －0.137 and －0.107, respectively, and both P<0.001). Negative coping style is positively correlated with the dimensions of organization and reward, demand and effort of occupational stress (r are 0.298 and 0.252, respectively, and both P<0.01), and negatively correlated with the social support dimension of occupational stress (r is －0.158, P<0.001).

Hierarchical regression analysis on the correlation among occupational stress, coping style and depressive symptoms

Hierarchical regression analysis is carried out by taking the depressive symptom score as the dependent variable, and the demographic characteristic variables, occupational stress and coping style dimension scores with statistical significance for depressive symptoms in Table 3 as independent variables. In the first layer, the demographic characteristic variables are included as the control variables, and the results show that the effects of education level and work system on depressive symptoms are statistically significant (both P<0.05). In the second layer, the four dimensions of occupational stress are included in the equation, and the results show that the effects of these four dimensions on depressive symptoms are statistically significant (all P<0.01), explaining the 15.7% of variation (P<0.001) in depressive symptoms, suggesting that occupational stress can directly affect depressive symptoms. In the third layer, the two dimensions of coping style are included in the equation, and the results show that the effects of these two dimensions on depressive symptoms are statistically significant (both P<0.001), which can explain 19.5% of variation in depressive symptoms (P<0.001), meanwhile the effects of four dimensions of occupational stress on depressive symptoms are statistically significant (all P<0.05). See Table 4.

Table 4 Hierarchical regression analysis on the relationship among occupational stress, coping style and depressive symptoms

Variables	Layer 1			Layer 2			Layer 3
Variables	β value	tvalue	95%CI value	β value	tvalue	95%CI value	β value	tvalue	95%CI value
Education level	0.061	2.441	0.084-0.767	0.058	2.525	0.090-0.718	0.052	2.561	0.084-0.634
Personal monthly income	－0.002	－0.065	－0.261-0.245	0.031	1.380	－0.070-0.401	0.018	0.919	－0.110-0.303
Average weekly working hours	0.038	1.543	－0.038-0.319	＜0.001	0.018	－0.163-0.166	－0.002	－0.117	－0.153-0.136
Shift work	0.069	2.908	0.247-1.269	0.095	4.212	0.555-1.523	0.071	3.625	0.360-1.207
Occupational stress
Social support				－0.238	－11.000	－0.361-－0.252	－0.134	－6.729	－0.223-－0.122
Organization and reward				0.165	6.518	0.122-0.226	0.054	2.390	0.010-0.104
Demand and effect				0.174	7.120	0.196-0.345	0.100	4.614	0.089-0.221
Autonomy				－0.066	－2.947	－0.271-－0.054	－0.049	－2.529	－0.217-－0.027
coping style
Positive coping style							－0.149	－7.874	－0.121-－0.073
Negative coping style							0.482	25.102	0.289-0.337
F value		5.401^a			52.446^a			118.240^a
R²value		0.010			0.168			0.363
Adjusted R²value		0.008			0.165			0.360
Increment of R² value					0.157			0.195

Note: β is normalized partial regression coefficients, R² is coefficients of determination. In the assignment of independent variables, Education level: junior high school and below=1, high school/technical secondary school=2, college or above=3. Personal monthly income: <¥ 3000=1, ¥ 3000-<¥ 5000=2, ¥ 5000-<¥ 7000=3, ≥¥ 7000=4. Average weekly working hours : ≤40 hours=1, 41~48 hours=2, 49~58 hours=3, 59~66 hours=4, ≥67 hours=5. Shift work: no=1, yes=2. The scores of various dimensions of occupational stress and coping style are continuous variables and not assigned values. ^aP<0.001. Blank items indicate that there is no data for this item.

Most of China's manufacturing workers are engaged in repetitive and uncreative work, and with the upgrading of the industrial structure, higher requirements have been put forward for the quality and technology of this population, coupled with the low sense of social identity and low welfare benefits, the mental health problems of this group have been attracting attention [32-34]. As a simple and effective screening scale for depression, PHQ-9 is widely used in the screening of depressive symptoms in China's occupational population. PHQ-9 is used to evaluate the depression of employees of 34 gene sequencing companies in China, and the results show that 427 employees have a depressive symptom detection rate of 33.5% (143/427) [35]. In the early investigation of the depression of assembly line employees in China's electronics manufacturing service industry, the detection rate of depressive symptoms is 31.0% (2,623/8,456) [36]. The detection rate of depressive symptoms in the study subjects of this survey is lower than that of the other groups mentioned above, which may be related to the different sample size of the survey and the type of work of the research subjects. On the other hand, it may be related to the formal implementation of the construction of healthy enterprises in China since 2018, which regard the health management of occupational groups as an important part of enterprise management, requiring attention not only to the prevention and treatment of statutory occupational diseases, but also to the prevention of mental health problems caused by work stress [37].

In this study, the detection rate of depressive symptoms of 2,083 manufacturing workers in China is 15.7%. A large number of domestic and foreign studies have shown that occupational stress has a significant positive effect on depression, the higher the degree of occupational stress, the greater the likelihood of depressive symptoms [38-41]. In this study, the depressive symptoms of 2,083 manufacturing workers in China are positively correlated with occupational stress and negative coping style (both P<0.001) and negatively correlated with positive coping style (P<0.001), while occupational stress is positively correlated with negative coping style (P<0.001) and negatively correlated with positive coping style (P<0.001). These suggest that occupational stress and negative coping style are risk factors for the occurrence of depressive symptoms, and positive coping style is a protective factor for reducing the occurrence of occupational stress and depressive symptoms. The results indicate that the higher the level of occupational stress and the more negative the coping style of manufacturing workers, the higher the risk of depressive symptoms. Among them, depressive symptoms are positively correlated with the dimensions of organization and reward, demand and effort of occupational stress (both P<0.001), and negatively correlated with the dimension of social support of occupational stress (P<0.001). It shows that organization and reward, demand and effort were risk factors for the occurrence of depressive symptoms, and social support is a protective factor for reducing the occurrence of depressive symptoms. The results show that the more promising and the better the job prospects, the higher the work requirements and level of effort required, the higher the expectations for the work, and the more likely they are to develop depressive symptoms [35]. Social support from leaders, co-workers, and family members can help reduce the risk of depressive symptoms [42,43].

In order to further clarify the correlation among occupational stress, coping style and depressive symptoms, this study adopt hierarchical regression analysis method, and first includes demographic characteristic variables with statistical significance of depressive symptoms as control variables, and the results show that the influence of work system on depressive symptoms is statistically significant (P<0.05). Then, the four dimensions of occupational stress are also included in the equation, and the results show that these four dimensions explain 15.7% variation of depressive symptoms (P<0.001), suggesting that occupational stress can directly affect depressive symptoms. Finally, the two dimensions of coping style are included in the equation, and the results show that these two dimensions of coping style have statistical significance in their effects of depressive symptoms (P<0.001), which explain 19.5% of the variation in depressive symptoms (P<0.001), meanwhile the four dimensions of occupational stress on depressive symptoms are statistically significant (P<0.05). It suggests that coping style has a moderating effect in the effect of occupational stress on depressive symptoms. Specifically, differences in coping style in the same stress environment will directly affect the degree of impact of individual occupational stress on depressive symptoms. Positive coping style is the ability of individuals to regulate their own psychological conditions, which is conducive to improving personal psychological level. Negative coping style has been shown to be significantly positively associated with depressive symptoms, with positive coping style predicting depressive symptoms, while positive coping style is the opposite [44]. Studies at home and abroad have shown that trait coping style is closely related to occupational stress, and coping styles can alleviate the impact of depressive symptoms caused by adverse states [45,46]. Those with a higher level of trait coping have fewer mental health problems, while those with a negative coping style tend to have more likely psychological problems. Therefore, in the face of work pressure, by cultivating positive coping ability, it has a positive effect on reducing occupational tension and reducing the occurrence of depressive symptoms. On the contrary, manufacturing workers who tend to adopt negative coping methods are likely to activate their negative self-perception and produce negative psychological experiences, which in turn increases the risk of depressive symptoms. If the working environment cannot be changed and improved in the short term, it is recommended to encourage and support manufacturing workers to adopt more positive coping methods, such as exercise intervention and mindfulness stress reduction [47-49], to alleviate the adverse effects of occupational stress, and to help them reduce negative coping styles through strengthening psychological training, so as to reduce the negative impact of occupational stress on depressive symptoms.

There are certain limitations in this study: i) the study subjects are only from manufacturing enterprises in Beijing City and Guangdong Provinces, and the samples are poorly representative. ii) The companies selected in this study are longitudinal study subjects, and psychological interventions have been taken on them in recent years, which may limit the generality of the results to a certain extent. iii) This study is a cross-sectional survey, and it is not possible to speculate about the causal relationship between variables. Subsequently, a multi-stage stratified cluster sampling method will be used to expand the scope and sample size of the study to improve the generalization and representativeness of the results.

This exploratory study shows that occupational stress can directly affect the occurrence of depressive symptoms in manufacturing workers of China. coping style has a moderating effect in the effects of occupational stress on depressive symptoms. In order to alleviate occupational stress and reduce the occurrence of depressive symptoms, enterprises should focus on workers with mental health problems and create a positive working atmosphere. Manufacturing workers should also constantly adjust their coping methods during their working time and daily life, and adopting positive and mature coping methods can help them perceive social and organizational support, so as to better mobilize their work enthusiasm, enhance their sense of work fulfillment, reduce their occupational tension and the risk of depressive symptoms. On the contrary, negative coping style is more likely to let the manufacturing workers have negative feelings about work, reduce their sense of job fulfillment, and increase the incidence of their depressive symptoms.

Acknowledgments

The authors would like to express their sincere gratitude to all field workers and participants of this study.

Authors’ contributions

XYL designed and wrote the manuscript. HQC analyzed and interpreted the findings, co-authored the manuscript. XQL, MQH and YG collected data and revised the paper. XML, JBC and SL designed, reviewed, and revised the manuscript and approved the final manuscript as submitted. All authors have read and approved the final manuscript.

Funding

This study is supported by the Central Financial Project of Occupational Health Institute, Chinese Center for Disease Control and Prevention (grant number 131031109000160008), Guangdong Medical Research Fund (grant number A2019498, B2019197 and B2023176), Foshan Medical Science and Technology Project (grant number 2020001005677)

Availability of data and materials

Original data are available on reasonable request. These were stored on password-protected computers at the National Institute of Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, China. Readers who wish to gain access to the data can write to the corresponding author.

Ethics approval and consent to participate

In accordance with the Declaration of Helsinki, the study protocol is approved by the Medical Ethics Committee of the National Institute of Occupational Health and Poison Control (Code No. NIOHP201914). All participants gave written informed consent before recruited into the study.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Guo X, Zhang JJ, Chi KW, et al. Study and policy suggestions on international competitive advantage of manufacturing industry among China, United States, Japan, and Germany[J]. Bulletin of Chinese Academy of Sciences,2023,38(8):1130-1153. https://doi.org/10.16418/j.issn.1000-3045.
(in Chinese)
Liu Y, Liang M, Xu S, et al. Current situation and copings strategies of China’s manufacturing offshoring--an analysis based on linkages in industrial chain and supply chain[J]. Intertrade,2023(5):3-13. https://doi.org/10.14114/j.cnki.itrade.2023.05.009. (in Chinese)
Zhang W, Li HY, Zhang T. Measuring the resilience of China’s manufacturing industry chain and its spatial-temporal differentiation[J]. Economic Geography,2023,43(4):134-143. https://doi.org/10.15957/j.cnki.jjdl.2023.04.014. (in Chinese)
Liu XM, Wang J, Zhang QY, et al. Job burnout and influencing factors among Chinese manufacturing employees[J]. J Environ Occup Med,2023,40(4):396-404. https://doi.org/10.11836/jeom22367. (in Chinese)

Chen H, Zhang QY, Gao QQ, et al. Impact of social support on early health effects of occupational stress in employees of electronic manufacturing service enterprises[J]. Chinese J Ind Med,2020,33(5):435-438. https://doi.org/10.13631/j.cnki.zggyyx.2020.05.016. (in Chinese)
Zhang BY, He Y. Research on achievements, problems and suggestions for manufacturing industry in China[J]. China Standardization,2023(16):18-22,32. https://doi.org/10.3969/j.issn.1002-5944.2023.16.001. (in Chinese)
Kim J, Kim HC, Kim M, et al. Occupational stress changes and new-onset depression among male Korean manufacturing workers[J]. Ann Occup Environ Med,2023,35:e33. https://doi.org/10.35371/aoem.2023.35.e33.

Guo J, Meng D, Ma X, et al. The impact of bedtime procrastination on depression symptoms in Chinese medical students[J]. Sleep Breath,2020,24(3):1247-1255. https://doi.org/10.1007/s11325-020-02079-0.

Babajide A, Ortin A, Wei C, et al. Transition cliffs for young adults with anxiety and depression: is integrated mental health care a solution?[J]. J Behav Health Serv Res,2020,47(2):275-292. https://doi.org/10.1007/s11414-019-09670-8.
Watanabe K, Imamura K, Kawakami N. Working hours and the onset of depressive disorder: a systematic review and meta-analysis[J]. Occup Environ Med,2016,73(12):877-884. https://doi.org/10.1136/oemed-2016-103845.
Santini ZI, Koyanagi A, Tyrovolas S, et al. The association between social relationships and depression: a systematic review[J]. J Affect Disord,2015,175:53-65. https://doi.org/10.1016/j.jad.2014.12.049.
Zhou S, Chen H, Liu M, et al. The relationship between occupational stress and job burnout among female manufacturing workers in Guangdong, China: a cross-sectional study[J]. Sci Rep,2022,12(1):20208. https://doi.org/10.1038/s41598-022-24491-0.

Segel-Karpas D, Ayalon L, Lachman ME. Retirement and depressive symptoms: a 10-year cross-lagged analysis[J]. Psychiatry Res,2018,269:565-570. https://doi.org/10.1016/j.psychres.2018.08.081.

Terms of occupational health promotion: GBZ/T 296-2017[S]. Beijing: Standards Press of China,2017.
Liu XM, Wang C, Wang J, et al. Effect of long working hours and insomnia on depressive symptoms among employees of Chinese internet companies[J]. BMC Public Health,2021,21(1):1408. https://doi.org/10.1186/s12889-021-11454-9.
Wang J, Zou RY, Wu N, et al. Depressive symptoms, social support, and health-related quality of life: a community-based study in Shanghai, China[J]. Compr Psychiatry,2022,113:152292. https://doi.org/10.1016/j.comppsych.2021.152292.
Kim HD, Park SG, Won Y, et al. Longitudinal associations between occupational stress and depressive symptoms[J]. Ann Occup Environ Med,2020,32:e13. https://doi.org/10.35371/aoem.2020.32.e13.
Li XY, Chen HQ, Wang J, et al. Association of occupational stress, job burnout and depressive symptoms of employees in labor-intensive enterprises[J]. Chin Occup Med,2022,49(1):29-33,40. https://doi.org/10.20001/j.issn.2095-2619.20222005. (in Chinese)
Tang AL, Thomas SJ. Relationships between depressive symptoms, other psychological symptoms, and quality of life[J]. Psychiatry Res,2020,289:113049. https://doi.org/10.1016/j.psychres.2020.113049.
Tao N, Zhang JJ, Liu JW. Effect analysis of trait coping style on job stress and job burnout of armymen in high and cold regions[J]. Chinese J Ind Med,2018,31(3):199-202. https://doi.org/10.13631/j.cnki.zggyyx.2018.03.015. (in Chinese)
Zhang JJ, Jia JM, Tao N, et al. Mediator effect analysis of the trait coping style on job stress and fatigue of the military personnel stationed in plateau and high cold region[J]. Chin J Ind Hyg Occup Dis,2017,35(3):176-180. https://doi.org/10.3760/cma.j.issn.1001-9391.2017.03.004. (in Chinese)
Zhou LP, Xu WF. Mediating effect of trait coping style on nurses' occupational stress and fatigue[J]. Chin J Prim Med Pharrn,2019,26(17):2087-2092. https://doi.org/10.3760/cma.j.issn.1008-6706.2019.17.010. (in Chinese)
Lei MY, Chen HY, Zhou HK, et al. Relationship between positive mental characters and depression symptoms among male new recruits: multiple mediation effects of trait coping styles[J]. J Third Mil Med Univ,2015,37(22):2237-2240. https://doi.org/10.16016/j.1000-5404.201508101. (in Chinese)
Li T, Li S. Healthy China Strategy and occupational health protection[J]. Chin Occup Med,2020,47(5):505-511. https://doi.org/10.11763/j.issn.2095-2619-2020.05.001. (in Chinese)
Wang J, Zhang QY, Chen HQ, et al. Development of the Core Occupational Stress Scale for occupational populations in China[J]. Chin J Prev Med,2020,54(11):1184-1189. https://doi.org/10.3760/cma.j.cn112150-20200319-00383. (in Chinese)
Wang J, Liu XM, Sun YY, et al. A preliminary study on establishment of the Core Occupational Stress Scale (COSS) norms for manufacturing and medical workers in China[J]. Chin J Prev Med,2020,54(11):1190-1196. https://doi.org/10.3760/cma.j.cn112150-20200430-00674. (in Chinese)
Wang XD. Handbook of mental health rating scales (updated edition)[M]. Beijing: Chinese Journal of Mental Health,1993:120.
Jiang QJ, Zhu YH. Further explorations for a coping style questionnaire[J]. Chin J Behav Med & Brain Sci,1999,8(3):167-169. (in Chinese)
Jin T. The reliability and validity of patient health questionnaire module (PHQ-9) in Chinese elderly[D]. Hangzhou: Zhejiang University,2010.
Martin A, Rief W, Klaiberg A, et al. Validity of the Brief Patient Health Questionnaire Mood Scale (PHQ-9) in the general population[J]. Gen Hosp Psychiatry,2006,28(1):71-77. https://doi.org/10.1016/j.genhosppsych.2005.07.003.
Wang J, Liu XM, Wang C, et al. Mediating role of psychological capital in occupational stress and depressive symptoms among employees working in an assembly-line of electronic manufacturing service industry[J]. Chin Occup Med,2019,46(3):280-285. https://doi.org/10.11763/j.issn.2095-2619.2019. 03.004. (in Chinese)

Xu JP, Wang XF, Zhao R. Status of occupational stress in employees of an electronic manufacturing enterprise and its intervention strategy[J]. Chin J Ind Med,2019,32(5):362-366. https://doi.org/10.13631/j.cnki.zggyyx.2019.05.006. (in Chinese)
Chen HQ, Chen JB, Li XL, et al. Effects of occupational stress on the level of salivary cortisol in electronic manufacturing workers[J]. Chin Occup Med,2018,45(6):727-730. https://doi.org/10.11763/j.issn.2095-2619.2018.06.013. (in Chinese)
Zhou Y, Liu XX, Zhao JJ, et al. Research on occupational stress and its influencing factors among workers in an automobile manufacturing enterprise[J]. Health Education and Health Promotion,2023,18(3):254-257. https://doi.org/10.16117/j.cnki.31-1974/r.202303254. (in Chinese)
Xu M, Yan TL, Xie TT, et al. Effect of occupational stress on depression and sleep of gene sequencing enterprise employees[J]. J Environ Occup Med,2022, 39(11):1256-1261. https://doi.org/10.11836/jeom22107. (in Chinese)

Sun YY, Wang J, Liu XM, et al. Prevalence of job burnout and associated influencing factors among healthcare workers in China[J]. J Environ Occup Med,2023,40(4):405-412. https://doi.org/10.11836/jeom22366. (in Chinese)
Li S, Li T, Ren J, et al. Thoughts and content framework on construction of health enterprises in China[J]. Chin Occup Med,2018,45(6):665-668. https://doi.org/10.11763/j.issn.2095-2619.2018.06.001. (in Chinese)
Rugulies R, Aust B, Madsen IE. Effort-reward imbalance at work and risk of depressive disorders. A systematic review and meta-analysis of prospective cohort studies[J]. Scand J Work Environ Health,2017,43(4):294-306. https://doi.org/10.5271/sjweh.3632.
Madsen IEH, Nyberg ST, Magnusson Hanson LL, et al. Job strain as a risk factor for clinical depression: systematic review and meta-analysis with additional individual participant data[J]. Psychol Med,2017,47(8):1342-1356. https://doi.org/10.1017/S003329171600355X.
Theorell T, Hammarström A, Aronsson G, et al. A systematic review including meta-analysis of work environment and depressive symptoms[J]. BMC Public Health,2015,15:738. https://doi.org/10.1186/s12889-015-1954-4.
Liu Y, Zhu XL, Wang L. Effects of occupational stress and doctor-patient relationship on depression tendency of medical staff[J]. Ind Hlth & Occup Dis,2020,46(4):268-270. https://doi.org/10.13692/j.cnki.gywsyzyb.2020.04.002. (in Chinese)
Shu C, Zhang D, Dai JM, et al. Effects of occupational stress and social support on depressive symptoms among employees from a state grid corporation[J]. J Environ Occup Med,2018,35(10):905-909,923. https://doi.org/10.13213/j.cnki.jeom.2018.17593. (in Chinese)
Li XY, Chen HQ, Zhou SY, et al. Study on relationship among occupational stress, job burnout and depressive symptoms in female workers of labor-intensive enterprises[J]. Chinese J Ind Med,2020,33(3):228-232,261. https://doi.org/10.13631/j.cnki.zggyyx.2020.03.007. (in Chinese)
Hong YL. Analysis of the role of trait coping styles in the association between occupational stress and depressive symptoms among CDC personnel[D]. Nanjing: Dongnan University,2022.

Zheng Z, Han W, Zhou Y, et al. Childhood maltreatment and depression in adulthood in Chinese female college students: the mediating effect of coping style[J]. Front Psychiatry,2020,11:581564. https://doi.org/10.3389/fpsyt.2020.581564.
Wang J, Yan XQ, Ling RJ, et al. Occupational stress, burnout, and coping styles among medical staff from a tertiary first-class hospital in Hubei Province[J]. Prev Med,2021,33(12):1203-1208. https://doi.org/10.19485/j.cnki.issn2096-5087.2021.12.003. (in Chinese)
Williams-Southers T. Relaxation methods to reduce occupational stress[J]. Workplace Health Saf,2023:21650799231184375. https:// doi.org/10.1177/21650799231184375.

Soteriades ES, Vogazianos P, Tozzi F, et al. Exercise and occupational stress among firefighters[J]. Int J Environ Res Public Health,2022,19(9):4986. https://doi.org/10.3390/ijerph19094986.
Yang J, Tang S, Zhou W. Effect of mindfulness-based stress reduction therapy on work stress and mental health of psychiatric nurses[J]. Randomized Controlled Trial,2018,30(2):189-196. https://doi.org/10.24869/psyd.2018.189.

No competing interests reported.

The correlation among occupational stress, coping style and depressive symptoms in 2,083 Chinese manufacturing workers

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