Depression and anxiety in Chinese expatriate employees in Misan oilfield in Iraq: A structural equation modeling approach

Abstract

BACKGROUND

Depression and anxiety symptoms are commonly found in expatriate workers employed in the oil industry and may be associated with occupational stress, age, rotation length, years of service, and local origin. However, the interrelations among these factors and their association with depression and anxiety symptoms in this population have not been examined. Therefore, the present work was undertaken to determine the clinical features of depression and anxiety symptoms in expatriate Chinese workers in the Misan oilfield in Iraq and to examine the interrelations between these symptoms.

AIM

To investigate depression and anxiety among Chinese oil workers in Iraq and model their interrelationships using structural equation modeling (SEM).

METHODS

A cross-sectional survey of Chinese oil employees was conducted using convenience sampling in the Misan oilfield in Iraq. The participants’ demographic characteristics, depression [Patient Health Questionnaire-9 (PHQ-9)], anxiety [(Generalized Anxiety Disorder-7 (GAD-7)], job burnout, occupational stress, and environmental stress were assessed. SEM was used to test hypotheses and to model the factors influencing depression and anxiety.

RESULTS

A total of 811 participants responded. Significant differences were observed in PHQ-9 scores based on education level (P < 0.05), smoking (P < 0.05), and drinking (P < 0.01) and in GAD-7 scores based on drinking (P < 0.05) and day and night shifts (P < 0.05). Iraqi social environmental and occupational stress, job burnout, and anxiety had direct effects on depression, and depression had direct effects on anxiety. In addition, indirect effects were found between social environmental and occupational stress on depression, primarily through job burnout. Social environmental and occupational stress and job burnout had indirect effects on anxiety, mainly via each other or through depression.

CONCLUSION

Education and smoking predicted depression, whereas shift work predicted anxiety. Drinking, overtime, environmental stress, occupational stress, and burnout directly and indirectly affected both conditions.

Key Words: Oil employees; Depression; Anxiety; Iraqi social environment stress; Occupational stress; Job burnout; Structural equation modeling

Core Tip: This study reveals a high prevalence of depression and anxiety symptoms in Chinese expatriate oil industry workers in Iraq. Such symptoms are associated with modifiable factors including smoking, drinking alcohol, shift work and excessive overtime work. Importantly, structural equation model analysis revealed that local social environment and occupational stress in Iraq can affect mental health directly or indirectly, mainly through the mediating effect of job burnout. The above findings suggest that interventions targeting job burnout may help alleviate the adverse psychological impacts of harsh working environments on this population.

INTRODUCTION

Depression and anxiety are the most common and highly harmful mental disorders. Conceptually, depression is typically defined by continuous low mood, lack of pleasure or engagement, and multiple mental and bodily symptoms, while anxiety involves excessive fear, worry, and related behavioral disturbances[1]. Per the findings of the Global Burden of Disease Study 2019, 301.4 million and 279.6 million people worldwide have anxiety and depressive disorders, respectively, with these numbers increasing substantially over the past 30 years[2]. Depressive and anxiety disorders account for a great disease burden, ranking among the top 2 positions among 12 mental disorders in terms of increased years of life lived with disability and greater disabilityadjusted life years[3]. Occupational factors such as shift work, job satisfaction, work environment, and work hours play an important role in mental health[4]. A recent meta-analysis has reported a higher prevalence of depression in industrial workers than in the general population[4].

The global oil industry employed 7.6 million people as of 2022[5]. These employees are more likely to be exposed to job-related threats (e.g., chemical toxins) together with environmental perils such as exposure to heat or cold, and solitary duty, and unhealthy working arrangements such as rotational shift scheduling and “fly-in fly-out” work arrangements[6], all of which may significantly affect their physical and mental health. These occupational stressors can negatively impact psychological distress through multiple pathways, including chronic activation of the stress response system, disruption of circadian rhythms and sleep due to shift work, social isolation, and reduced support networks. Several studies have indicated a higher prevalence of anxiety disorders and depression in oil industry workers compared with the general public. A report conducted in an offshore oil and gas company in the Middle East showed that nearly 15% of the workers had symptoms of anxiety and depression[7]. A cross-sectional survey among Chinese oilfield workers indicated that approximately 20% of participants suffered from psychological abnormalities[8]. During the coronavirus disease 2019 pandemic, the prevalence rates of stress, depressive and anxiety symptoms among offshore oil platform workers rose to 25.9%, 24.6% and 30.5% respectively[9].

Notably, expatriate employees account for a large proportion of the workforce in the petroleum industry. They reside abroad for work purposes and return to their home countries upon completion of their assignments. Oil-producing countries in the Middle East have the highest proportion of expatriate workers in the petroleum sector, whose numbers often exceed those of local employees[10]. Expatriate workers are prone to cultural shock, separation from extended families, adaptation difficulties, heightened stress and other issues that elevate the risk of mental health disorders[11]. Against this backdrop, existing studies on the mental health of expatriate staff in the Middle Eastern petroleum industry have yielded valuable insights, yet several limitations remain. Most investigations focus on general expatriate groups or local oil workers across the Middle East, while studies specifically targeting Chinese expatriates are scarce. Several studies have explored the correlation between occupational psychological stress and emotional health among expatriate workers in the petroleum industry. However, local social environmental stressors unique to the Middle East, such as regional unrest and cultural differences, have rarely been incorporated into research frameworks. In addition, the mechanisms by which various stressors including job burnout mediate the development of depressive and anxious emotions remain unclear, which hinders in-depth clarification of the inherent influencing pathways underlying mental health issues in this population. The above research gaps indicate that it is urgently necessary to focus on the mental health status of Chinese expatriate workers in high-stress Middle Eastern countries represented by Iraq, and further explore the interactions between various stress factors and mental health outcomes.

Earlier investigations have revealed that the psychological wellbeing of oil sector employees is correlated with occupational stress, age, shift duration, working years and native place and other factors[7-12]. Despite these findings, several critical research gaps still exist. Firstly, this study specifically targets Chinese expatriate oil workers employed in Iraq, filling the research deficiency regarding Chinese expatriates working in Iraq’s petroleum industry under such high-pressure regional circumstances. Secondly, this study established a mediation model incorporating local social environmental stress, integrating occupational stress, local social environmental stress and job burnout into a unified framework to explore their combined effects on depression and anxiety. Third, this study clarifies the intermediate function of occupational burnout between environmental stress (occupational and local social environmental stress) and depression/anxiety, thereby clarifying the intrinsic pathway through which stress factors affect the mental health of this vulnerable group. To this end, this study sought to explore the clinical features of depression and anxiety symptoms in the group of Chinese expatriate workers in the Misan oilfield in Iraq, using SEM. The study also was designed to investigate the reciprocal connections connecting clinical features of depression with those of anxiety, and to verify the mediating role of job burnout in the association between environmental stress and mental health outcomes.

MATERIALS AND METHODS

Study population and data collection

This nonexperimental investigation used a onetime observational assessment of Chinese oil employees recruited using convenience sampling from the Misan oilfield in Iraq. This research was performed from April 2024 through June 2024 in line with the Declaration of Helsinki (revised in 2013) and was reviewed and approved by the Ethics Committee of Shanghai Tongji Hospital. All participants provided written notified consent prior to enrollment. The participants had the option to discontinue the survey at any point. Any data that could identify the subjects remained private.

In total, 916 subjects finished the survey. However, 105 were excluded from subsequent analyses due to the following reasons: (1) Informed disagreement (n = 6); (2) Unreasonable response time, defined as total response time less than the number of items multiplied by 2 seconds (n = 64)[13]; (3) Careless responses, with the long string coefficient (i.e., the maximum number of same consecutive responses on a single page) exceeding the mean by 0.4 standard deviations[14] (n = 32); and (4) Outliers (n = 3). The final sample size was 811, resulting in an effective response rate of 88.54% (age: 40.03 ± 7.27, range: 21-59, 98.89% men). The sample size satisfied the suggested requirements for SEM, which propose a minimum n of 200 for maximum likelihood estimation[15]. A flowchart of participant selection is presented in Figure 1.

Figure 1 The flowchart of participant selection.

Demographics and working conditions

A demographic questionnaire was designed to collect data on age, marital status, sex, educational level, smoking, number of children, drinking, and exercise. Information regarding work conditions, including vocational type, day and night shifts, working days, and overtime hours (hour/week), were collected.

Patient Health Questionnaire-9

The Patient Health Questionnaire-9 (PHQ-9) scale consists of 9 items, which is used to screen depressive symptoms and assess the severity of symptoms among subjects in the past two weeks. It has been validated in various medical settings with satisfactory reliability, and its Cronbach’s alpha coefficient ranges from 0.86 to 0.89[16]. The total score of the scale ranges from 0 to 27, and higher scores indicate more severe depressive symptoms.

The Generalized Anxiety Disorder-7

The Generalized Anxiety Disorder-7 (GAD-7) scale contains 7 self-rated items, which is applied to screen generalized anxiety disorder and evaluate the severity of anxiety symptoms of participants over the past two weeks. It has favorable reliability and validity among primary care attendees and general populations, with a Cronbach’s alpha coefficient of 0.89[17]. The total score ranges from 0 to 21, and higher scores reflect more severe anxiety symptoms.

Maslach Burnout Inventory General Survey

This study adopted the Maslach Burnout Inventory General Survey to assess the level of job burnout. As a self-rating scale, it comprises 16 items covering three dimensions: Cynicism, emotional exhaustion and professional efficacy. A 7-point Likert scoring method was applied (0 = never, 6 = every day), with higher scores indicating severer job burnout. The psychometric properties of this scale have been verified in various populations. It presents good internal consistency reliability, with the overall Cronbach’s alpha coefficient ranging from 0.71 to 0.84[18].

The Core Occupational Stress Scale

The Core Occupational Stress Scale is a 17-item self-rated scale comprising four dimensions: Social support, salary and organization, demand-effort, and self-control. It adopts a 5-point Likert scoring system, ranging from 0 (strongly disagree) to 5 (strongly agree). The overall reliability of the scale (Cronbach’s α = 0.97) and the reliability of its subscales (Cronbach’s α = 0.72–0.91) have been verified among Chinese petroleum workers[19].

Iraqi social pressure

The Iraqi social pressure is a self-rated questionnaire developed according to the population characteristics of oilfield workers in Iraq. Adopting a 5-point Likert scoring method (0 = no impact at all, 4 = great impact on work), this scale is used to assess the degree of occupational stress caused by the unique local social environment in Iraq. The questionnaire contains 10 items: “Turbulent and unstable social environment”, “Local religious beliefs, culture, and taboos”, “The phenomenon of local armed gun ownership and the presence of other military equipment in Iraq”, “Frequent checkpoints by local personnel when travelling within and outside the oilfields”, “Marches, demonstrations, roadblocks, and strikes related to the oilfields and beyond”, “News events about unrest in Iraq”, “Field travel tasks in Iraq”, “Local Iraqi temperature and climate, geography or wildlife, etc.”, “Odor, noise, dust, etc. while working as local expatriate staff”, and “Different working habits, style, and languages while working with foreign employees”. Respondents were requested to rate their job stress in each of the above situations, and a higher score corresponds to a higher degree of environmental stress.

Statistical analysis

Descriptive statistics of the demographic and study variables were tabulated to obtain a preliminary understanding of the participants’ basic information and working conditions. Analysis of variance, independent-samples t-test, and correlation analysis were conducted to examine the differences and correlations between the PHQ-9 and GAD-7 scores according to demographic characteristics. SEM was used to test specific hypotheses to model the factors influencing depression and anxiety. After applying the exclusion criteria, there were no missing data for any variable of interest among the 811 participants, as the online survey platform required responses to all items before submission. Therefore, all 811 participants were included in the final SEM analysis.

The preference for SEM over alternative multivariate techniques stemmed from its capacity to incorporate several outcome variables into a single analytical framework, simultaneously controlling for the indirect effects among the interconnected dependent measures. Furthermore, the framework enables the direct integration of latent variables (i.e., factor analysis structures) into linear equations that specify relationships between latent and observed constructs.

However, several indices need to be confirmed before SEM. The accuracy and consistency of the scales were examined using exploratory factor analysis and Cronbach’s alpha reliability. The Kaiser-Meyer-Olkin (KMO) test and Bartlett’s test of sphericity served to evaluate data suitability. The following criteria were adopted: KMO > 0.60, with > 0.90 considered ideal[20]; Bartlett’s P < 0.05. Cronbach’s alpha, representing the internal consistency reliability of the latent variables, value of > 0.6 was considered acceptable[21].

The fit of the SEM was evaluated in the next step. Confirmatory factor analysis (CFA) is a test of the fitness of theoretical models and data. Factor loading, average variance extracted (AVE), and construct reliability (CR) are important statistical indicators for testing the model fit[22]. The following criteria were adopted: CFA ≥ 0.60[23]. The AVE of each scale should be larger than the correlation of the specific scale with any other scale in the model and should be at least 0.50[24]. CR exceeding 0.70 was considered indicative of acceptable reliability[25].

The fit between the data and the measured and hypothesized models was assessed using the following fit indices: χ², normal χ², comparative fit index (CFI), Tucker-Lewis index (TLI), standardized root mean square residual (SRMR), and root mean square error of approximation (RMSEA)(14). Bootstrapping functioned to assess the statistical importance of the direct and indirect effects in the hypothesized model in the multiple mediation analysis. The following criteria were adopted: χ² and division is performed by the degrees of freedom (χ²/df) to minimize the dependence on sample size. Ideally, the number should be three or less[26]. CFI and TLI ≥ 0.90. SRMR and RMSEA should be ≤ 0.1. A zero value denoted that the model fit exactly, close fit; and 0.05-0.08, acceptable fit[27]. Accordingly, this study adopted the threshold of 0.08. All data examinations were conducted with SPSS 23.0 and Mplus version 7.0. Statistical significance was set at P < 0.05.

RESULTS

General characteristics of the participants

Over 75.83% of the participants had received not less than a high school education, and 87.18% were married. More than half were front-line workers (n = 660, 81.38%), and the arithmetic mean of consecutive days on duty in the current round was 94.39 days (SD = 101.23), the average number of overtime hours per week was 7.96 hours (SD = 9.72), and 31.07% worked day and night shifts (Table 1).

Table 1 General characteristics of the participants, n (%)/mean ± SD.

Latent variables	Category			Range		PHQ-9			GAD-7
							Levene	F/r		Levene	F/r
Demographic characteristics
Sex	Male	802 (98.89)				3.44 ± 3.87	2.42	0.51	2.23 ± 3.24	5.26b	2.55
	Female	9 (1.11)				2.78 ± 2.17			1.11 ± 1.27
Age (years)	Total			21-59	40.03 ± 7.27			-0.07			-0.07
	18-25	23 (2.84)				4.3 ± 3.66	1.60	0.96	3.43 ± 3.65	2.63b	2.20
	26-35	185 (22.81)				3.58 ± 3.65			2.35 ± 3.04
	36-45	409 (50.43)				3.35 ± 3.77			2.04 ± 3.13
	46-55	182 (22.44)				3.25 ± 3.92			2.19 ± 3.30
	56-60	12 (1.48)				4.92 ± 7.53			4.08 ± 5.95
Education	Junior high school and below	196 (24.17)				3.75 ± 5.04	13.01c	3.45b	2.55 ± 4.14	8.90c	2.25
	High school/technical school	178 (21.95)				2.94 ± 3.78			1.80 ± 3.11
	Junior collegea,b	162 (19.98)				2.90 ± 2.91			1.98 ± 2.59
	Bachelor degree or abovea,b	275 (33.91)				3.83 ± 3.31			2.39 ± 2.86
Marriage	Single	61 (7.52)				4.18 ± 3.39	1.21	1.10	2.67 ± 3.22	1.28	0.46
	Love/engagement	24 (2.96)				4.04 ± 2.93			2.29 ± 2.20
	Married	707 (87.18)				3.34 ± 3.87			2.17 ± 3.23
	Divorce/widowhood	19 (2.34)				3.47 ± 5.18			2.32 ± 4.18
Children	Zero	107 (13.19)				4.26 ± 3.44	0.47	2.44	2.86 ± 3.25	1.44	1.98
	One	269 (33.17)				3.51 ± 4.06			2.17 ± 3.20
	Two	394 (48.58)				3.20 ± 3.78			2.13 ± 3.31
	Three or more	41 (5.06)				2.90 ± 3.97			1.63 ± 2.35
Smoking	Yes	431 (53.14)				3.70 ± 4.12	3.19	-2.11b	2.35 ± 3.47	4.89b	-1.32
	No	380 (46.86)				3.13 ± 3.50			2.06 ± 2.93
Drinking	Yes	256 (31.57)				4.07 ± 3.65	0.57	-3.24c	2.64 ± 3.23	0.55	-2.58b
	No	555 (68.43)				3.13 ± 3.91			2.02 ± 3.21
Exercise habit	Yes	722 (89.03)				3.42 ± 3.83	1.92	0.17	2.21 ± 3.23	2.00	0.24
	No	89 (10.97)				3.49 ± 4.00			2.29 ± 3.24
Job information
Vocational type	Manager	128 (15.78)				3.90 ± 3.65	0.91	1.47	2.84 ± 3.16	1.99	2.97
	Front-line workers	660 (81.38)				3.36 ± 3.92			2.11 ± 3.26
	Maintenance worker	23 (2.84)				2.70 ± 2.82			1.74 ± 2.07
Day and night shifts	Yes	252 (31.07)				3.30 ± 3.45	5.35b	-0.69	1.85 ± 2.81	12.01c	-2.31b
	No	559 (68.93)				3.49 ± 4.02			2.38 ± 3.39
Working days (current consecutive)				0-630	94.39 ± 101.23			0.04			0.05
Overtime hours/week (hour)			0-72	7.96 ± 9.72			0.14c			0.13c

^aP < 0.05, education level with a bachelor’s degree or above showed significantly higher Patient Health Questionnaire-9 scores than those with a junior college degree.

^bP < 0.05.

^cP < 0.01.

PHQ-9: Patient Health Questionnaire-9; GAD-7: Generalized Anxiety Disorder-7.

Depression and anxiety according to participant characteristics

Depression: PHQ-9 scores differed significantly based on education level (P < 0.05), smoking (P < 0.05), and drinking (P < 0.01). A follow-up post-hoc analysis revealed that workers with a bachelor’s degree or above had more PHQ-9 scores vs those with a junior college degree (P < 0.05). Those who smoked and consumed alcohol had significantly higher PHQ-9 scores than those who did not (P < 0.01). Correlation analysis revealed that more overtime hours were associated with higher PHQ-9 scores (P < 0.01) (Table 1).

Anxiety: GAD-7 scores differed significantly based on drinking habits (P < 0.05) and working day and night shifts (P < 0.05). Post-hoc analysis revealed that workers who consumed alcohol had significantly higher GAD-7 scores than those who did not (P < 0.05). Workers who did not engage in day and night shift work had significantly higher GAD-7 scores than those who did (P < 0.05). Correlation analysis revealed that more overtime hours exhibited an association with higher GAD-7 scores (P < 0.01) (Table 1).

Structural equation model analysis

Reliability and validity analysis: Reliability and validity analyses were conducted on the scales involved in the SEM, with Cronbach’s alpha = 0.84-0.92, KMO = 0.87-0.94, and Bartlett’s P < 0.01. The results supported further analysis (Table 2).

Table 2 Descriptive statistics of the measured variables, mean ± SD.

Latent variable	Range		Cronbach’s α	KMO	Bartlett’s test/χ² test	AVE	CR
PHQ-9	0-27	3.43 ± 3.85	0.89	0.92	3273.64a	0.54	0.91
GAD-7	0-21	2.22 ± 3.23	0.92	0.93	3639.67a	0.68	0.94
MBI-GS	0-55	18.22 ± 13.19	0.89	0.92	10333.69a	0.71	0.97
COSS	17-66	39.07 ± 9.56	0.84	0.87	8311.17a	0.70	0.97
ISP	0-25	4.98 ± 5.80	0.92	0.94	4781.64a	0.6	0.94

^aP < 0.01.

PHQ: Patient Health Questionnaire-9; GAD-7: Generalized Anxiety Disorder-7; MBI-GS: Maslach Burnout Inventory General Survey; COSS: Core Occupational Stress Scale; ISP: Iraqi social pressure; KMO: Kaiser-Meyer-Olkin test; CR: Construct reliability; AVE: Average variance extracted.

CFA: The CFA of the measurement items demonstrated that each variable had standardized loadings spanning 0.56-0.94 and AVEs spanning 0.54-0.71. Since these figures equaled or exceeded 0.5, convergent validity was confirmed. The peak correlation value among the measurement variables reached 0.78, indicating their conceptual unrelatedness. For every pair, the AVE exceeded the square of their intercorrelation, thereby establishing discriminant validity. The CR estimates between 0.91 and 0.97, each exceeding 0.7, which indicates satisfactory internal consistency.

Model fit: Both the measurement model and the hypothesized model complied with the recommended fit index standards. The overall model fit was therefore accepted as satisfactory (Table 3).

Table 3 Hypothetical model fit.

	χ2	df	χ2/df	TLI	CFI	SRMR	RMSEA
Recommended criteria	-	-	< 3	> 0.9	> 0.9	< 0.05	< 0.08
Measurement model	1252.56	485.00	2.58	0.91	0.92	0.047	0.04
Hypothesized model	1863.86	485.00	3.84	0.90	0.91	0.047	0.06

TLI: Tucker-Lewis index; CFI: Comparative fit index; SRMR: Standardized root mean square residual; RMSEA: Root mean square error of approximation.

Path analysis for the hypothetical model

The pathways between the variables are presented in Figure 2 and Table 4. Because correlations among independent variables are default assumptions in SEM statistics, the immediate and mediated path coefficients were adopted to indicate the magnitude of the associations between the examined constructs.

Figure 2 Structural equation model of depression and anxiety. Ovals represent latent variables and solid arrows, direct empirical relationships between the variables. ^aP < 0.05; ^bP < 0.01.

Table 4 Standardized direct, indirect, and total effects.

Pathways	Direct effect	Indirect effect	Total effect
Iraqi social environmental stress → depression	0.13a	0.41b	0.54b
Occupational stress → depression	0.14a	0.24b	0.38b
Job burnout → depression	0.57b	-	0.57b
Anxiety → depression	0.75b	-	0.75b
Iraqi social environmental stress → anxiety	0.03	0.47b	-
Occupational stress → anxiety	0.08	0.32b	-
Job burnout → anxiety	-0.04	0.49b	-
Depression → anxiety	0.87b	-	0.87b
Iraqi social environmental stress → job burnout → depression	-	0.25b	-
Iraqi social environmental stress → occupational stress → job burnout → depression	-	0.10b	-
Occupational stress → job burnout → depression	-	0.24b	-
Iraqi social environmental stress → depression → anxiety	-	0.11b	-
Iraqi social environmental stress → job burnout → depression → anxiety	-	0.22b	-
Iraqi social environmental stress → occupational stress → job burnout → depression → anxiety	-	0.08b	-
Occupational stress → depression → anxiety	-	0.12a	-
Occupational stress → job burnout → depression → anxiety	-	0.21b	-
Job burnout → depression → anxiety	-	0.49b	-

^aP < 0.05.

^bP < 0.01.

Iraqi social environmental stress (β direct = 0.13, P < 0.05; β indirect = 0.41, P < 0.01) and workrelated strain (β direct = 0.14, P < 0.05; β indirect = 0.24, P < 0.01) showed significant direct and indirect associations with depression. Nevertheless, job burnout (β direct = 0.57, P < 0.01) and anxiety (β direct = 0.75, P < 0.01) revealed only direct associations with depression, but no significant indirect associations were observed. Two significant indirect pathways were identified regarding the indirect associations of environmental stress on depression. First, social environmental stress had a significant positive indirect association with depression via job burnout (β indirect = 0.25, P < 0.01). Second, a serial mediation pathway was identified between social environmental stress and depression, with occupational stress and job burnout as mediating variables (indirect = 0.10, P < 0.01). The substantial indirect effect of occupational stress on depression was mediated by job burnout (β indirect = 0.24, P < 0.01).

Social environmental stress (β direct = 0.03, P > 0.05), occupational stress (β direct = 0.08, P > 0.05), and job burnout (β direct = -0.04, P > 0.05) showed no direct associations with anxiety. However, indirect associations were observed. Two important pathways were identified: The indirect association of occupational stress on anxiety, with depression as a mediating variable (β indirect = 0.12, P < 0.05), and the indirect association mediated sequentially by job burnout and depression (β indirect = 0.21, P < 0.01). Three pathways were observed regarding the effect of Iraqi social environmental stress on anxiety: The indirect associations of the social environmental stress with anxiety with depression as a mediating variable (β indirect = 0.11, P < 0.01), with job burnout and depression as sequential mediating variables (β indirect = 0.22, P < 0.01), and with occupational stress, job burnout, and depression as sequential mediating variables (β indirect = 0.08, P < 0.01). The indirect association of job burnout on anxiety was mediated by depression (β indirect = 0.49, P < 0.01).

DISCUSSION

This onetime observational study used SEM to investigate the clinical features of depression and anxiety symptoms and their associations among Chinese expatriate oil employees in the Misan oilfield in Iraq. Consistent with previous findings[6,7], the sample exhibited elevated depression and anxiety symptoms relative to general population norms, though mean PHQ-9 (3.43) and GAD-7 (2.22) scores were below clinical thresholds. To our current knowledge, this research is the inaugural study to investigate the interplay of factors of depression and anxiety symptoms among expatriate oilfield workers.

Demographic analysis revealed several significant regularities: Migrant workers with higher educational levels presented more obvious depressive symptoms. This finding is consistent with previous studies, which indicated that highly educated individuals are more susceptible to cross-cultural adaptation stress and occupational stress[28,29]. This phenomenon is particularly prominent among expatriates living in unfamiliar social environments[28,29]. This phenomenon may be particularly relevant to expatriates working in unfamiliar social environments. Overtime hours were significantly associated with depressive and anxiety symptoms, which not only confirms the evidence obtained from large-scale studies conducted among Chinese and Japanese employees[28,29], but also extends its applicability to the context of oilfields in Iraq. Consistent with the viewpoints proposed by Parkes[30], excessive overtime may impair sleep duration and quality, serving as a reasonable explanatory mechanism linking occupational demands to impaired mental health.

An unexpected finding merits further discussion. Workers without day-night shift work presented significantly higher anxiety levels than shift workers, which seemingly contradicts meta-analytic evidence indicating that shift work elevates anxiety risks[31,32]. Nevertheless, this counterintuitive result can be reasonably explained by analyzing the unique occupational characteristics of our study sample. At the Missan Oilfield, non-shift employees are mostly long-term on-site managers, engineers and supervisors who bear disproportionate responsibilities for production safety, project management and emergency response. As stated by Kim et al[33], prolonged working hours with blurred boundaries between work and rest may trigger chronic hypervigilance and anxiety symptoms. Such conditions are less common among shift workers, who have fixed off-duty and rest hours compared with non-shift expatriate managerial staff. In addition, non-shift workers usually lack regular rest schedules and are less likely to obtain team social support commonly available under shift work arrangements. Accordingly, this correlation result reflects the physical and mental burdens caused by long-term high-intensity job responsibilities, rather than the mere absence of shift work systems. It also provides an important reference for enterprises to formulate targeted intervention strategies.

Regarding environmental stress pathways, both social environmental stress and occupational stress can affect depressive and anxious emotions directly or indirectly. This is consistent with findings of numerous studies, which have confirmed that occupational stress acts as a risk factor triggering mental health problems in various occupations such as offshore oilfield workers[7,12,34-36]. Based on previous literature, this study specifically focuses on expatriate workers, who are exposed to unique stressors that local employees do not encounter. As Jones[37] stated, expatriates frequently suffer from insufficient family support, increased workload, physical fatigue, as well as cultural and ethnic differences, all of which can further aggravate work stress. A recent study on the Middle Eastern petroleum industry indicated that local employees suffered from more severe anxiety and depressive symptoms than expatriates[7]. Such differences stem from distinct types of stress endured by the two groups. Local employees are mainly troubled by social unrest and unstable economic situations, while expatriates are more plagued by social isolation and difficulties in cultural adaptation.

The innovation of this study lies in exploring the unique social environmental stress in Iraq. The self-developed Iraqi social pressure was adopted to evaluate stress induced by regional unrest, local religious beliefs, widespread weapons, distribution of military facilities and other relevant factors. Independently compiled by the research team, this scale possesses sound psychometric properties, with Cronbach’s alpha coefficient greater than 0.9 and KMO value higher than 0.9. This study verified that the local social environment in Iraq can affect depression and anxiety both directly and indirectly, with job burnout and occupational stress serving as mediating variables in such influencing pathways. This finding is in line with previous evidence documenting an elevated depression prevalence exceeding 50% among the general population and student groups in Iraq[38,39], which has been attributed to three decades of prolonged warfare, violent incidents and economic crises. Similarly, the Global Burden of Disease Study[2] has confirmed the high prevalence of depression and anxiety in the Middle East, further highlighting the important public health guiding significance of the findings of this study for this region.

Path analysis revealed theoretically meaningful differential influencing patterns: Environmental stress can directly affect depressive symptoms, while it exerts only an indirect effect on anxiety symptoms, which is fully mediated by depression and/or job burnout. This result is consistent with the hierarchical progressive model stating that depression precedes anxiety[12], suggesting that depressive symptoms tend to emerge earlier in occupational settings and further trigger anxiety symptoms. This temporal sequence provides a theoretical basis for implementing early targeted interventions centered on depression to prevent secondary anxiety. This study verified that job burnout serves as a stable and reliable mediating variable, with a particularly prominent mediating effect on depression, which is in line with the academic consensus that long-term workplace stress most readily induces job burnout directly[18]. Job burnout exerts a significant indirect effect on anxiety via depression (indirect effect β = 0.49), indicating that alleviating job burnout can produce a linkage effect to simultaneously improve both depressive and anxious negative emotions.

Our study has several limitations. First, the retrospective cross-sectional study design limited the ability to make causal inferences and to interpret the associations. In addition, the unique characteristics of the sample may limit the generalizability of the findings to a larger population. Furthermore, the Iraqi social environmental stress questionnaire was author-designed and consisted of items covering different social environmental items, lacking reliability and validity validation. Caution should be exercised regarding the interpretation of the related results. The data were gathered via an internetbased survey; therefore, some responses could have been incomplete, or certain data points could be missing. Additionally, participants were assessed in person; making it difficult to fully verify eligibility criteria.

Second, the gender distribution of the sample was highly imbalanced, with nearly all participants being male. Although this reflects the occupational reality of frontline oilfield work, it also means that the results cannot be generalized to female expatriate employees, who may experience different or additional stressors. Third, several important confounding variables that have been proven to be closely related to depression and anxiety-such as past or family history of mental illness, level of social support (e.g., from family or colleagues), and coping strategies (e.g., problem-focused vs emotion-focused)-were not assessed[40,41]. The absence of these variables may have affected the accuracy and comprehensiveness of the model, and may have contributed to an overestimation of the observed associations between environmental stress, occupational stress, and mental health outcomes. Fourth, despite the identification of several significant pathways, the cross-sectional design precludes definitive conclusions regarding temporal precedence or causal direction. Fifth, the objective measures of sleep quality or quantity, which are known to be associated with shift work, overtime, and mental health outcomes[30]. Finally, the adoption of self-rating scales may lead to common method bias, although the results of reliability and validity analyses are satisfactory.

Further studies adopting cohort study designs, recruiting larger and more diverse samples including female expatriates, conducting face-to-face assessments, and comprehensively evaluating psychiatric history, social support and coping strategies are required in the future. Meanwhile, more detailed and in-depth evaluations on the associations between Iraqi social environmental stress and depressive as well as anxiety symptoms are warranted.

CONCLUSION

This study found that among Chinese expatriate oil employees working at the Missan Oilfield in Iraq, educational level and smoking were correlated with depressive symptoms, while day-night shift work was associated with anxiety symptoms. Alcohol consumption and overtime hours were significantly related to both depressive and anxiety symptoms. In addition, Iraqi social environmental stress, occupational stress and job burnout exerted direct and/or indirect effects on depressive and anxiety symptoms, and job burnout served as the core mediating variable linking environmental and occupational stress to mental health outcomes.

Based on these findings, interventions should prioritize the reduction of job burnout given its core mediating role. Specifically, workplace interventions can be carried out from the following three aspects: (1) Control total working hours and limit consecutive on-duty days. In this study, the average consecutive working days of the participants was 94.39 days with a standard deviation of 101.23 days; (2) Optimize the shift scheduling system to ensure sufficient rest time and clarify the boundary between work and rest. Special attention should be paid to non-shift workers, who are burdened with long-term high-intensity work duties and prone to persistent mental tension; and (3) Regularly conduct mental health monitoring and job burnout assessment, focusing on frontline staff responsible for work safety and project management as well as long-term on-site managers.

Given the unique practical dilemmas in Iraq including social unrest, widespread firearms and cultural differences, targeted pre-departure cultural adaptation training should be provided for expatriates, and a regular mental health support system should be established locally. Further longitudinal follow-up studies are required to clarify the temporal associations among various variables and verify the practical effects of the interventions proposed in this study.

ACKNOWLEDGEMENTS

The authors thank the Iraqi Branch of China National Offshore Oil Corporation and Tongji Hospital of Tongji University for their significant support in this study. The authors are grateful for the technical support of VIA MEDICA International Healthcare and Hechangzhineng for their assistance.