The Demand-Control model and work-related threats and violence: Short- and long-term associations

Abstract

BACKGROUND:

Work-related violence and threats are frequent in human service sectors. Although previous studies have identified several psycho-social work environmental risk factors for work-related violence and threats, the research domain still remains mainly descriptive and non-theoretical in nature.

OBJECTIVE:

Using the Job-Demands-Control model we analysed the relationship between the psycho-social work environment and work-related threats and violence.

METHOD:

Using a two-wave (2011 and 2015) longitudinal study of 2678 participants, we analysed the main and interactive effects of quantitative demands and job control on exposure to work-related violence and threats.

RESULTS:

High work demands and low job-control were associated with elevated risk of work-related threats in 2011 and in 2015. The associations of work demands and job control and work-related violence were mixed. There were not statistically significant interaction effects between high demands and low job control on neither work-related violence nor threats.

CONCLUSION:

In sectors where work-related threats and violence are likely to occur, risk prevention may also require improving the work conditions for employees, more specifically by reducing work-demands and increasing job control for instance by differentiating between important and less important work demands and by implementing self-autonomous work-teams may be a way to increase job control.

Keywords

1 Introduction

Work-related violence has been defined as “any incident in which a person is abused, threatened or assaulted in circumstance related to their work” [1]. In this study, work-related violence is defined as threats and violence perpetrated by patients/clients/pupils or prisoners and directed at the employees at their workplace during working hours. This definition excludes threats and violence perpetrated by supervisors and colleagues and exclude incidents that has taken place during leisure time.

Previous studies show a high prevalence of work-related violence towards employees in the social service and health sectors [2 –4]. Furthermore, research has found that health care is ranked among the most dangerous sectors for nonfatal workplace assault injuries [5]. Such injuries may result in various forms of psychological distress, including post-traumatic stress disorder (PTSD) and disability [6]. Understandably, many employees in these occupations regard work-related violence as a serious work environment problem [7]. Therefore, identifying risk factors can provide a basis for designing intervention programmes to prevent or reduce the frequency of work-related violence and threats.

1.1 Risk factors for work-related violence

Work-related violence is a complex phenomenon, with no single cause being sufficient to explain why some employees are exposed to work-related violence and others are not [8]. Studies have found that risk factors at the individual level such as being young, having less job experience and holding a lower rank in the organization are associated with higher risk of work-related violence [9, 10]. However, these individual factors seem to occur as a result of the interaction between the persons involved and factors in the social context [8]. Accordingly, several studies have explored risk factors at the workplace level, focusing on specific work environment factors that could increase the risk of work-related violence and threats. Specifically, workplace factors including high demands, high work pressure, low role clarity, poor social climate and social support, high emotional demands, low levels of involvement at the workplace, lower leadership quality, and role conflict have been found in association with elevated risk of work-related violence and threats [11 –14].

An important limitation of these studies is that they are mainly cross-sectional, with only a few adopting a longitudinal design. For instance, a follow-up study including 3011 participants found that high quantitative and emotional demands, as well as high role conflict, were associated with heightened levels of work-related threats and violence [11].

Another important limitation of previous studies is that they have addressed an extensive list of work environment factors potentially associated with work-related violence and threats [11, 14]. Statistically, this is problematic because including many factors in a single regression model may lead to multicollinearity, which entails unstable and uninterpretable estimates. Theoretically, this approach is problematic due to the lack of a solid theoretical model on which to test associations and to further theoretical development. Using theory-driven models of the psychosocial work environment such as the well-established Job-Demands-Control Model [15], may therefore enhance our understanding of the specific working conditions that can increase the risk of work-related violence and threats.

1.2 The Job Demand-Control model

The Job Demand-Control model (JDC) distinguishes between two crucial aspects of the job, namely psychological demands (work load, unexpected tasks and job-related interpersonal conflicts) and job control (ability to control own work situation, autonomy and skill discretion). The model posits that the combination of high job demands and low job control (the strain hypothesis) results in the most adverse reactions in terms of psychological strain and physical illness [16]. However, job control gives employees the opportunity to have decisional authority on how they handle the required work, as well as to restructure the pacing, the timing and the methods used in accomplishing the work tasks [17]. Thus, high job control is expected to moderate the negative effects of job demands on employee health and well-being.

Many studies have applied the JDC model to a broad array of outcomes such as mortality, angina pectoris, mental strain and psycho-somatic symptoms. As pointed out by Baillien et al. [18], behavioural outcomes of the model are rare and have only been addressed in terms of work-performance and health-related behaviour. Some studies responded to this gap by testing the strain hypothesis of the JDC model in relation to workplace bullying, finding that high strain was associated with targets’ reports of bullying and that job control moderated such association [18, 19].

1.3 The JDC model and work-related violence and threats

While the previous mentioned studies highlight the predictive ability of the JDC model in relation to workplace incidents such as bullying, it is still unknown whether the model is capable to predict other forms of aggressions, including work-related violence and threats.

Both empirical findings and theoretical arguments support the integration of the JDC model into the research on the antecedents of work-related violence and threats. Empirical studies have shown positive associations between high workload and work-related violence. For instance, victims of work-related violence have been found to often experience high qualitative and emotional job demands and low control over own work situation [11 , 14].These work characteristics are at the core of the JDC model. From the theoretical viewpoint, a link between the JDC model and risk of work-related violence can be expected because situations of high job demands and low job control may increase work-related strain (for a review, see Häusser et al. 2010 [20]) which, in turn, may decrease job performance in terms of disrupted continuity of care, increased errors and undermined quality of care and service [21, 22]. Care recipients and service users (e.g., patients, client, pupils, and prisoners) may, in turn, react in violent and threatening manners in the face of errors, mistakes or blunders that occur in conditions of heavy work load, high work pressure and low job control [18, 23].

To date, only a few studies have used the JDC model to explore the relationship between the work environment and work-related violence and threats. Two studies found that high demands were a significant predictor of threats and emotional abuse; however, job control was not associated with work-related violence or threats, and no interactive effects were observed [13, 24]. The validity of these findings is, however, limited due to methodological shortcoming such as small samples sizes, low response rates, the use of a cross-sectional design and the inclusion of nurses and midwives exclusively, which makes generalization difficult.

1.4 Study aim and hypotheses

The aim of the present study is to examine whether high levels of work-related work demands and low levels of job control (i.e., job strain) affect the report of work-related violence and threats in four high-risk occupational sectors. Specifically, the following hypotheses were tested:

High quantitative demands at work are positively related to reports of work-related violence and threats.

Low job control is positively related to reports of work-related violence and threats.

The association between high demands at work and work-related threats and violence is moderated by job control, i.e. the association decreases when job control is higher.

2 Material and methods

2.1 Participants

The study sample is based on a Danish cohort established in 2010 [4], with follow-up surveys carried out in 2011 and 2015. The associations between work demands and job control measured in 2010 and work-related threats and violence measured in 2011 are reported elsewhere [11]. In this study, we want to examine the long-term associations between work demands and job control measured in 2011 and work-related threats and violence measured in 2015. We included those employees who participated in the 2011 and 2015 waves of the study.

The cohort consisted of employees working in psychiatric wards, in the elder care, at special schools (schools for pupils with severe developmental and intellectual disabilities) and in the Prison and Probation Service. The participants employed in psychiatric wards, elder care homes and at special schools received and filled out paper-and-pencil questionnaires during a planned meeting at the worksite. A web-based questionnaire was used for participants in the Prison and Probation Services –a decision made by top management. The invited participants were persons employed in jobs involving contacts with clients and with no record of absence spells of more than three weeks prior to the time the questionnaires were distributed. The last criterion was to ensure that employees were sufficiently aware of the present psycho-social work environment at their workplace. The procedure for data collection is described in detail elsewhere [4]. In the questionnaire, the participants were informed that participation in the study was voluntary and that the participants could withdraw from the study at any time. According to Danish Law, approval by the Ethics Committee and written and informed consent is not required in questionnaire-based and register-based projects.

In 2010, 5,333 employees participated. Altogether, 3,751 participated in 2011. In 2015, the data collection was based on invitations sent to all participants from 2010 who were still living in Denmark. Using their civil registration number, we were able to contact them by mail, regardless of whether they were still employed at their original workplace. A total of 3,486 employees participated in 2015.

In this study we included all those participants who filled out the questionnaires both in 2011(N = 3751) and in 2015 (N = 2,675) given a response rate of 76.7%.

2.2 Questionnaires

2.2.1 Predictor: Quantitative demands at work

The job demands component of the JDC model was operationalized in terms of quantitative demands at work. The latter was measured with the Copenhagen Psychosocial Questionnaire (COPSOQ), a standardized instrument designed to probe different aspects of the psychosocial work environment [25].

The scale includes four items (sample item: Do you have time enough for your work tasks?), to be answered using five Likert-type response options, ranging from ‘always’ (5) to ‘never’ (1). Missing items were deleted from the analysis (listwise).

The Cronbach’s alpha for the quantitative demands at work scale was 0.82.

2.2.2 Moderator: Control over own work situation

Control over own work situation was measured with the COPSOQ.

The scale included four-items (sample item: Do you have a large degree of influence concerning your work?) to be answered using Likert-type options, ranging from '’always (5) to ‘never’ (1). Missing data were deleted from the analysis (listwise).

The Cronbach’s alpha for control over own work situation scale was 0.77.

2.2.3 Outcome measure: Work-related violence and threats

Based on Wynne, Clarkin, Cox and Griffeths (1997), we applied a broad definition of work-related violence that includes threats of violence as well as physical violence [26]. Specifically, we used a checklist consisting of 11 different types of violent incidents and seven different types of threats of violence used in previous research in Sweden [27]. Types of physically violent behaviors were being spit on, being hit, being hit with object, being scratched/pinched, being shoved, being held, being punched with a fist, being kicked, being bit, having a hard object thrown at you, and using of a weapon or a weapon like object. Threatening behaviors included being threatened with beatings, written threats, in a scolding manner, in an insulting manner, over the phone, being threatened involving objects, and indirectly (i.e. towards family). Respondents were asked to indicate how often during the past year they had experienced each of these different types of threats or violence at their workplace. For both work-related violence and threats, the frequency of occurrence was measured by means of a five-point Likert scale, ranging from never (0) to almost daily (4). First, the items (11 different types of violent incidents and seven different types of threats of violence) were computed into two sum scales, which were labelled ‘threats of violence’ and ‘physical violence’, respectively. Next the ‘threats of violence’ and ‘physical violence’ scales were dichotomized into two groups. Those exposed the work-related threats and violence respectively and those not exposed to work-related threats or violence respectively. Missing items were deleted from the analysis (listwise).

The Cronbach’s alpha work-related threats scale was 0.80 and for work-related violence scale, the Cronbach’s alpha was 0.89

2.2.4 Confounders

Background information about gender, age, and the working hours spent in direct contact with patients, clients, pupils or prisoners were retrieved from the baseline survey. The latter factor was measured by asking participants to report the proportion (in percentage) of their working time spent in direct contact with recipients. The response categories were <25%, 25–49%, 50–75% and >75%.

2.3 Statistical analysis

The data did not meet the statistical assumptions of normality and homoscedasticity required for multiple linear regression [28]. We therefore applied hierarchical logistic regressions and calculated odds ratios, along with their 95% confidence intervals (CI), for the associations of quantitative demands and job control with work-related violence and work-related threats. The two scales were dichotomised by contrasting those exposed to work-related threats and violence versus employees not-exposed.

Quantitative demands and job control were continuous scales.

In the first block of the regression analysis, we entered the control variables (sex, age, working time spent contact with clients, and, only for the longitudinal analysis, baseline exposure to work-related threats and violence). In the second block, we entered the quantitative demands and job control, while in the final block we added the interaction between quantitative demands and job control.

3 Results

The sample characteristics are shown in Table 1. The mean age of the participants was approx. 45 years. The employees were very experienced and the majority of participants were women. The frequency of work-related violence and threats was high both in 2011 and in 2015.

Table 1
Descriptive data of participants

Number of participants 2011: 3751 2015: 3486 Follow-up: 2675

Mean /SD

Age 43.40/10.31

Work experience at actual workplace 8.22/8.02

Working time with client contact 2.78/1.03

Demands at work 2.48/0.77

Job control 2.91/0.78

n %

Sex Male 905 33.8

Female 1770 66.1

Any threats during past year 2011 Yes 1628 63.0

No 965 37.0

Any violence during past year 2011 Yes 889 34.7

No 1675 65.3

Any threats during past year 2015 Yes 1499 34.2

No 780 65.8

Any violence during past year 2015 Yes 904 39.5

No 1383 60.5

Age, sex, work experience, contact with clients, demands and job control was measured in 2011

Number of participants	2011: 3751	2015: 3486	Follow-up: 2675
		Mean /SD
Age		43.40/10.31
Work experience at actual workplace		8.22/8.02
Working time with client contact		2.78/1.03
Demands at work		2.48/0.77
Job control		2.91/0.78
		n	%
Sex	Male	905	33.8
	Female	1770	66.1
Any threats during past year 2011	Yes	1628	63.0
	No	965	37.0
Any violence during past year 2011	Yes	889	34.7
	No	1675	65.3
Any threats during past year 2015	Yes	1499	34.2
	No	780	65.8
Any violence during past year 2015	Yes	904	39.5
	No	1383	60.5
Age, sex, work experience, contact with clients, demands and job control was measured in 2011

Table 2 shows the main and interaction effects of quantitative demands and job control in 2011 on work-related threats and violence in both 2011 and 2015 (the latter after adjusting for baseline levels of work-related threats and violence, respectively). High quantitative demands and low job control (main effect) were associated with an increased risk of reporting work-related threats in both years. The main effects of quantitative demands and job control on work-related violence were mixed. High quantitative demands were significantly associated with increased risk of work-related violence only in 2011. Job control was significantly associated with increased risk for violence in 2015, but not in 2011.

Table 2

The main and interaction effects of quantitative demands and job control in 2011 on work-related threats and violence in 2011 and in 2015

	Work-related threats		Work-related violence
	2011	2015	2011	2015
Block 1	OR	OR	OR	OR
Sex	1.88 (1.61–2.01)^***	1.86 (1.51–2.30)^**	0.94 (0.81–1.10)	1.32 (1.07–1.61)^**
Age	1.04 (1.03–1.04)^***	1.02 (1.02–1.03)^***	1.02 (1.01–1.03)^***	1.01 (0.99–1.02)
Time with clients	1.52 (1.41–1.70)^***	1.47 (1.35–1.61)^***	1.70 (1.53–1.84)^***	1.46 (1.26–1.69)^**
Baseline threats or violence	5.21 (3.70–7.30)^***	8.20 (6.33–10.51)^**
Block 2
Quantitative demands	1.32 (1.20–1.45)^***	1.18 (1.04–1.34)^*	1.16 (1.05–1.18)^*	1.01 (0.88–1.14)
Job control	1.42 (1.27–1.58)^***	1.43 (1.24–1.65)^***	1.02 (0.98–1.15)	1.25 (1.08–1.45)^*
Block 3
Quantitative demands^*jobcontrol	1.03 (0.90–1.18)	0.94 (0.78–1.13)	0.94 (0.83–1.08)	1.08 (0.91–1.29)

^*p < 0.05, ^**p < 0.01, ^***p < 0.001.

4 Discussion

The current study set out to empirically investigate whether the JDC, could be predictive of work-related threats and violence in four high-risk occupations. Corroborating previous studies [3 , 30], we found a high prevalence of work-related threats and violence in both 2011 and 2015.

The results show that the main effects of high quantitative demands and low job control are more consistent with regard to risk of work-related threats in comparison to risk of physical violence.

Both high quantitative demands and low job control were related to increased risk of work-related threats, supporting the notion that an adverse psycho-social work environment may act as fertile ground for the occurrence of aggressive behavior [13, 18]. High levels of job demands and low levels of job control may wear out employees’ resources and lead to difficulties in coping with potential aggressive users.

However, with regard to risk of work-related physical violence, high quantitative demands increased risk for work-related violence in 2011, but not in 2015. Further, low job control increased risk for work-related violence in 2015, but not in 2011. One explanation might be that work-related violence is more strongly associated with risk factors embodied in tasks such as compulsory treatment, caring or controlling and less with work-environment [10 , 31–33] Furthermore, even though threats are often antecedents for violence, different risk factors may exist.

We found no interaction effects between high demands and low job control on work-related threats. This is in line with a previous review concluding that the evidence for interactive effects, as predicted by the buffer hypotheses of the Job Demands-Control model, is very weak [16].

Many studies have applied the JDC model to many different health outcomes. We extended the model by including social behavioural outcomes in the form of work-related violence and threats. In relation to work-related threats, our results are in line with a previous study using the JDC model to explain another social behavioural outcome, namely bullying at work [18]. Thus, the JDC model seems to have explanative power in relation to different types of workplace aggression, also including work- related threats. The JDC model does, however, seem not to be useful in explaining work-related violence. Our results are in line with earlier studies examining the association between the JDC model and work-related violence and threats. For instance, some studies have found, among nurses, that high demands were a predictor of threats, but neither of the mentioned studies observed significant associations between low control and work-related violence [13, 24]

4.1 Strengths and limitations

The present study has some important strength. First, the response rates were high and above the mean for organizational surveys [37]. Second, we examined participants from four sectors, which may increase generalizability. Finally, the study is based on a longitudinal design.

Yet, the results of the present study should be considered in the light of some limitations. First, in three sectors (eldercare, special schools and psychiatric wards), the participants were not representative of the respective population, since the data derived from convenience samples of employees coming primarily from two regions in Denmark. Even though the total sample size was large, these organizations were recruited using a non-random sampling method. Second, as some workplaces refused to participate, we cannot rule out selection bias, which may reduce the external validity of the findings. Third, modes of data collection were different across the four sectors, as web-based questionnaires were used in Prison and Probation Service and paper and pencil questionnaires in the other sectors. This may have introduced selection bias. If only employees showing interest in the topic responded, this may have inflated the associations, especially in the Prison and Probation Services wherein the lowest response rate was observed. Fourth, only healthy employees participated in the current study; those on sick leaves, including leaves due to work-related violence and threats, did not participate, which may lead to an underestimation of the associations between psychosocial work environment factors and work-related threats and violence. Fifth, the data came entirely from self-reports, which may introduce mono-method bias due to unmeasured third variables [38]. Final, the results must be interpreted with caution as there may be specific sector associations which may be blurred when the four sectors are analysed together. For instance, the possibility for high control may be different in schools and prisons.

5 Conclusion

We studied the relationship between work-related violence and a well-established theoretical model, the Job-Demands-Control Model, in four sectors with high risks of work-related threats and violence. We found that high demands and low job control increased the risk of work-related threats.

By using the JDC model, we have pointed to possible pathways between psycho-social work environment factors and work-related threats and violence. The relationship between high demands, high level of control and work-related threats points to possible interventions strategies. To reduce the risk of work-related threats, improving the work conditions for employees may be a recommendation, more specifically by reducing work-demands and increasing job control. Furthermore, to differentiate between important and less important work demands may be a way of reducing work demands and implementing self- autonomous work-teams may be a way to increase job control.

As far as we know, this study is the first in a follow-up design to examine the JDC model in relation to work-related threats and violence and therefore, more research is needed. First, more longitudinal studies with larger sample sizes and, both shorter and longer follow-up intervals are needed. Furthermore, future research may also examine the effect of other moderators, both work- and person-related, of the examined relationship. Finally, future research may investigate these pathways more specifically, by examining potential mediating variables between work environment and work-related threats and violence (e.g. the mediating effect of burn-out, depression).

Conflict of interest

None to report.

Footnotes

Acknowledgment

This research was supported by The Danish Working Environment Research Fund. Grant number 20090023636.

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