Workplace stress

As a consequence of the changing nature of work and the impact of globalisation, workplace stress is an issue of increasing importance in the developing world. Workplace stress has been defined by the WHO as a "pattern of physiological, cognitive and behavioural reactions to some extremely taxing aspects of work content, work organisation and work environment".

There are two key models that have been developed to understand the impact of psychosocial stressors at work. The first is the demand-control model, which characterises jobs according to the level of demand on the employee and the level of control he or she is able to exert. The combination of high demands and low control is described as job-strain and is associated with the highest risk for developing CMDs. Job-strain is inequitably distributed, as workers in lower skill level jobs are most likely to be affected with depression. Furthermore, other adverse health outcomes have been associated with job-strain, including heart disease and musculoskeletal problems, which in turn add to the impact of psychological stress.

Second, the effort-reward imbalance model characterises jobs according to the balance between the effort made by the employee and the rewards received, which include financial rewards, esteem, prospects of promotion and job security. Psychological stress is most associated with employment in which the rewards do not match the effort made.

In reality, it should be noted that the demand-control and effort-reward imbalances are intertwined and ought to be seen as integrated when considering the adverse impact of workplace conditions and also when considering potential workplace interventions to reduce the risk of CMDs.

The pattern of prevalence of CMDs in the workforce is similar to that found in the general population. Regarding the assessment of the impact of mental illness on work productivity, different measures have been used. These include: loss days, or the number of days during which respondents were unable to do their usual activities; cutback days, or the number of days during which activities were reduced; and extra effort days, or the number of days during which individuals were able to function normally but only with significant effort. The cost of working days lost in the European Union due to stress-related illness is estimated to be on average 3–4% of GDP. Estimates are that in the UK stress in the workplace causes a loss of 6.5 million working days a year.

In a review of five studies assessing the prevalence of mental disorders, Sanderson and Andrews (2006) found that depression and anxiety disorders were most commonly reported. The studies reviewed included the National Comorbidity Survey (NCS) from the USA, the Australian National Survey of Mental Health And Well-Being (ANSMHWB), the NEMESIS study in the Netherlands, the Ontario Mental Health Supplement in Canada and the UK Household Survey of Psychiatric Morbidity. Individuals with mental disorders were found to have a greater risk of non-participation in the workforce, although this conclusion is limited by the fact that studies have been conducted in developed countries.

The National Comorbidity Survey (NCS) study estimated that 3.6% of workers in the US labour workforce suffer from major depression and 18% of the workforce suffers from some form of mental illness at any point in time. Furthermore, people with depression were found to have an increased likelihood of experiencing comorbid physical disabilities, which may in turn have a negative impact on workplace productivity.

The NCS Replication study by Kessler et al (2006) assessed the association between mood disorders and impairment in the workforce more specifically. In this study of 3,378 workers in the USA, 6.4% met criteria for major depressive disorder. Work performance was assessed using the WHO Health and Work Performance Questionnaire, incorporating self-report regarding absenteeism and presenteeism. Presenteeism refers to the situation in which an employee attends work but is unable to work at their full capacity as a result of their illness; the impact of this issue has become of increasing concern to employers. It has been postulated that presenteeism may be of particular relevance to people with CMDs, as they may be less likely to report mental illness as a reason for missing work. Depressive disorders were found to have a significant effect on work performance. The authors' projections led to an estimate of 225 million workdays lost productivity per year associated with major depressive disorder across the USA labour workforce.

The NEMESIS study reported excess loss days of 28.9% for individuals with affective disorders and 17.6% for those with anxiety disorders. Similar associations were reported in the ANSMHWB report but not the NCS. However the NCS did report that all affective and anxiety disorders were associated with significant cutback days, and this pattern was consistent with that reported for both affective disorders and generalised anxiety disorder in Australia, and anxiety disorders alone in Ontario.

The Mental Health Economics European Network (MHEEN) Report (2005) confirmed the high prevalence of mental health morbidity in the workplace across the European Union. In Sweden for example, 27% of all cases of long-term sick leave are accounted for by mental health problems. In Austria, although there was a reduction in total days of absenteeism between 1993 and 2002, the proportion of total days of absenteeism that was related to mental health problems increased by 56%. In Germany, there was a significant increase of long-term sickness due to mental illness over a similar time frame.

In order to investigate the association between depression severity and job performance, Adler et al (2006) followed a cohort of 286 patients identified with major depressive disorder and/or dysthymic disorder and compared them with 93 patients with rheumatoid arthritis and also 193 control subjects. The cohort was followed over 18 months, and at the last time point the depression group had significantly greater deficits in job performance than either the rheumatoid arthritis or the control group. Furthermore, job performance remained static between the 6-month and 18-month intervals, reinforcing the chronic nature of disability that can result from depression. However this study has major limitations with respect to the generalisability of the findings as the enrolled participants were predominantly white and only 7% were employed in labouring jobs.

In a cohort study of 6,239 employees, selected at random from three major public corporations in the USA, Druss et al (2001) demonstrated similar findings regarding the impact of depression on work performance. This study was more representative of the general population with 43.7% of participants being of non-White racial background. Participants completed surveys regarding health and their satisfaction with health care between 1993 and 1995. Those who reported depressive symptoms were more likely to be female, were younger, less well educated and were more likely to have comorbid medical problems. This study highlights the association between CMDs and absenteeism. The odds of absenteeism due to health reasons were twice as high for employees with depressive symptoms. More significantly, this study highlighted the impact of presenteeism. Druss et al (2001) found a significant association between depressive symptoms and reduced effectiveness at work. In one year of the study the odds of decreased effectiveness at work in people with chronic depressive symptoms was seven times that of people without depressive symptoms.

Coworkers and supervisors may also be affected by the impaired performance of individuals with CMDs. Coworkers may need to perform additional work to compensate, and hence there is a "spillover" effect on others in the workplace. This is particularly the case where employees work as part of a team; a stressed group of workers will clearly not function as efficiently, which in turn leads to reduced productivity. Furthermore, mental illness may lead to "spillover" effects on the individual's family members, who may themselves be employed or engaged in other social responsibilities.

It is important to acknowledge that the inter-relationship between emotional wellbeing and work productivity is complex. People with CMDs may persist with work yet remain unproductive due to personal reasons, workplace culture and stigma. Workplace culture may also promote the view that CMDs are a sign of individual weakness rather than recognising psychiatric illness as arising from an interaction between the individual and his or her environment and recognising the availability of effective treatments. The treated prevalence of CMDs in society in general and the workplace in particular is low. Individual employees may not recognise that they are suffering from anxiety or depression, and may lack motivation to seek assistance. Furthermore, even if the employee recognises that they are suffering, they may be fearful of negative consequences if they overt their condition to their employers.