Research Plus: April/May 2008

Work factors can predict depression

Swedish research on the impact of work factors on anxiety and depression employed external assessment to overcome potential bias identified in previous studies, namely over-reporting of unfavourable work characteristics by those with psychiatric conditions. The study was based on 672 men and women in different occupations. Work characteristics and clinical diagnosis were assessed by interview. Externally assessed lack of instrumental social support at work (OR 6.4; 95% CI 2.6–15.8) and deteriorating work characteristics (OR 2.8, 95% CI 1.3–6.1) were associated with an increased risk for depression, even after controlling for mental illness symptoms at baseline, but were not significant for anxiety.

Occupational & Environmental Medicine 2008; 65; 90–96.

Hypertension and occupational exposures

Research undertaken as part of the Helsinki Heart Study followed changes in systolic blood pressure (SBP) over an eight-year period in 884 workers. High physical workload was associated with a statistically significant increase in SBP, but physical workload alone – ie without hypertension – was not a risk factor for coronary heart disease (CHD). Hypertension (SBP ≥ 140 mmHg) is a prerequisite for increased risk of CHD in this group of workers. Neither shiftwork nor noise exposure significantly raised SBP.

Scandinavian Journal of Work, Environment & Health 2007; 33(6) 425–434.

Long-term absence review

A systematic review uncovered 16 factors reported as significantly associated with long-term sick leave; however, evidence was generally weak. The study was restricted to cohort studies of workers on sick leave for more than six weeks; just five papers met inclusion criteria. There were four work-related factors – low job satisfaction, low degree of skill discretion, working for a non-profit organisation and a perception of not being welcomed back at work – and 12 individual factors. There is insufficient evidence to substantiate 14 of the factors, since these were identified only in single studies. Older age and a history of sickness absence were significant factors in two studies.

Occupational and Environmental Medicine 2008; 65: 153–157.

Obesity and presenteeism

US research finds that worker obesity is linked to lower productivity. A total of 341 blue- and white-collar employees in eight manufacturing companies completed anthropometric measurements and baseline surveys, including the Work Limitations Questionnaire. Participants were grouped into four categories according to body mass index. Moderately or extremely obese (BMI ≥ 35) workers experienced the greatest health-related work limitations, specifically with regard to the time needed to complete tasks and their ability to perform physical job demands.

Journal of Occupational & Environmental Medicine 2008; 50(1): 39–45.

Solvent-induced hearing loss

An evidence review on ototoxicy examined the effects of human exposure to styrene on the auditory system. Study populations varied from 16 to more than 500 workers, with exposure levels established from direct measurement of airborne styrene, biological monitoring, or estimates based on company records and questionnaire data. Nine studies were analysed, seven showed some effects on the auditory system associated with styrene exposure alone (ie noise exposure was not a factor). Reported effects are generally negligible and usually sub-clinical and it is not possible to identify dose–response relationships. The authors note the limitations of using pure-tone audiograms for investigating hearing damage due to styrene exposure owing to possible effects on the central nervous system.

International Journal of Occupational Medicine and Environmental Health 2007; 20(4): 315–325.

Predicting job loss

A literature review identified many possible risk factors for long-term incapacity from work. However, when 82 multifarious factors were assessed in a retrospective study of OH records from 741 employees, five factors emerged as strong predictors of a failure to return to work: patients’ own assessments of their ability to work; length of sickness absence in the previous 12 months; age; whether the patient was waiting for treatment or consultation; and patients’ perceptions of barriers to their return to work.

Occupational Medicine 2008; 58: 99–106.

Burnout lacks causal evidence

A literature review on the causes of so-called burnout in service workers found that while it remains a popular concept, the quality of available evidence is poor: most studies are cross-sectional preventing any clear identification of its causes. Work stressors, such as role ambiguity, job demands, and social support, and negative affectivity at individual level, have shown reasonably consistent associations with burnout. There is some evidence that interventions can be successful, though it is unclear how they might work.

London: Health and Safety Executive 2008, Research Report 610.

Hospital-based exercise RCT

A randomised control trial – albeit on a small scale – demonstrates that moderate exercise can be incorporated successfully into working hours in an NHS setting, and can significantly improve measured physical capacity and cardiovascular health. Twenty healthy full-time employees in sedentary jobs (microscopy) at a London hospital were randomly assigned either to a 12-week progressive aerobic exercise programme (four times a week) or control group. Peak oxygen consumption improved in the exercise group, as did economy of absolute oxygen utilisation at both 2 and 4 minutes. C-reactive protein concentration, a biological marker of inflammation, which may predict cardiovascular disease risk, was lowered.

Journal of Occupational Medicine and Toxicology 2008; 3: 7; doi: 10.1186/1745-6673-3-7.

Back pain training

A meta-analysis found no evidence to support the use of advice or training in working techniques, with or without lifting equipment, for preventing back pain or consequent disability. Eleven studies met inclusion criteria. The authors conclude that either the techniques had no effect on the risk of back injury, or that the training did not lead to sufficient modification in lifting or handling technique. Increasing the intensity of training made little difference.

British Medical Journal 2008; online first: doi: 10.1136/bmj. 39463.418380.BE,

Ototoxicity of industrial solvents

A second review of literature from 1980 to 2007 examined the effects of two common industrial solvents, styrene and toluene, on hearing. While there is conclusive evidence for ototoxicity for both solvents in rats, the existing evidence does not establish any dose–response/ effect relationships in humans. There is ‘some evidence’ that workers face a greater risk of hearing loss when simultaneously exposed to toluene and noise compared to exposure with noise alone, better quality research is needed.

Critical Reviews in Toxicology 2008: 38: 127–170.