Research Plus: April/May 2009

Does workplace exercise reduce back pain?

A systematic review found strong evidence that workplace exercise regimes are effective in reducing the severity of low back pain (LBP) and its impact on activity. However, owing to poor research quality and conflicting results, there is only ‘limited’ evidence that such regimes prevent LBP incidence and associated sick leave. Of the 15 papers meeting inclusion criteria only four were of high methodological quality. More evidence is needed to determine which exercises are effective and whether or not there is a dose–response relationship.

Journal of Occupational Rehabilitation 2009; 19(1): 8–24.

Mental health interventions

Workplace interventions can be effective in reducing depression and anxiety symptoms; however, a systematic review and meta-analysis finds that the effects are small. Twenty-two papers, covering 3,409 employees, met inclusion criteria; 17 were included in a meta-analysis of standardised depression and anxiety scores. Roughly half the studies focused specifically on mental health outcomes, and were based on cognitive behaviour interventions or coping skills training. The others were aimed at reducing risk factors, such as poor work environment, physical inactivity or cardiovascular disease. Standardised mean differences were 0.28 for depression (95% confidence interval 0.12–0.44) and 0.29 for anxiety (0.06–0.51). Interventions with a direct focus on mental health had similar beneficial effects as those aimed at reducing risk factors.

Scandinavian Journal of Work, Environment and Health 2009; 35(1): 7–18.

Influenza vaccine effectiveness research

Research papers concluding in favour of influenza vaccination are more likely to be of lower methodological quality than those casting doubt on their effectiveness. A systematic review on the effectiveness of influenza vaccine identified 259 papers, mostly on healthy populations. Notably, while 70% of the papers concluded in favour of vaccine use, only 18% had complete agreement between the reported data and the authors’ conclusions. Methodological quality was strongly associated with concordance between data and conclusions – in other words, the higher the quality of the study the lower the risk of bias. Industry-funded studies were more likely to conclude vaccine effectiveness and more likely to be published in high-impact journals despite being of similar study quality and size to government-funded studies.

British Medical Journal 2009; 338: b354, doi:10.1136/bmj.b354

Cancer survival and employment

A meta-analysis of 26 papers (covering 36 studies) finds that working-age people who survive cancer are more likely to be unemployed compared with healthy individuals, and this is especially so for survivors of breast and gastrointestinal cancers. The studies, including 15 from Europe and 16 from the US, covered 20,366 cancer survivors and 157,603 healthy controls; average age at diagnosis was 40–56 years; and mean follow-up time after diagnosis was nine months to 15 years. Cancer survivors were more likely to be unemployed at follow-up (33.8%) than healthy controls (15.2%): pooled relative risk = 1.37. (95% confidence interval 1.21–1.55).

Journal of the American Medical Association 2009; 301(7): 753–762.

Carpal tunnel syndrome

A systematic review (44 papers) of occupational risk factors for carpal tunnel syndrome (CTS) finds that the condition is strongly associated with high levels of hand-arm vibration, prolonged work with a flexed or extended wrist, high requirements for hand force (greater than 4 kg) and combinations of these. However, there was no evidence of psychosocial risk factors and contradictory evidence linking CTS with computer use.

Scandinavian Journal of Work, Environment and Health 2009; 35(1): 19–36.

Genito-urinary cancers and cadmium

A literature review by the Industrial Injuries Advisory Council found only ‘limited evidence’, in nine papers, of increased risk of bladder cancer associated with occupational exposure to cadmium. The only significant effect was found in a single case-control study; there was no supportive evidence from cohort studies. Of 10 papers investigating associations between occupational cadmium exposure and renal cancer, one case-control study found a doubling of risk from at least six years’ exposure, but this was not supported by long-term cohort studies. There was no evidence from 15 papers linking workplace cadmium exposure to prostate cancer.

Position Paper 24. London: The Industrial Injuries Advisory Council, 2009.

Holidays improve health and wellbeing

A meta-analysis finds that vacations have small positive effects on health and wellbeing, but the benefits fade rapidly on returning to work. There was insufficient evidence to analyse the health and wellbeing effects of different holiday activities, though one paper reports that positive vacation experiences result in improved wellbeing on return to work (negative experiences had the opposite effect). There was limited evidence that vacation satisfaction and negative work reflection may influence outcomes. Studies were not of high quality.

Journal of Occupational Health 2009; 51(1); 13–25.

Low-back pain and recovery expectation

A systematic review of non-specific low-back pain concludes that recovery expectations, measured in the early (non-chronic) stages of pain onset, and with regard to a specific time frame and defined outcome, are good predictors of poor outcome. For example, in predicting when they might return to work, individuals will take account of the tasks involved in their job and are able to predict relatively accurately when they will be able to do them. However, expectations of non-specific risks, such as developing future chronic pain or non-recovery, are poor indicators. Expectations measured within the first three weeks of pain are more strongly predictive than those measured later.

Journal of Occupational Rehabilitation 2009; 19(1): 25–40.

Work stress and dysmenorrhoea

One in five women in a study of 821 pre-menopausal, non-pregnant female employees in Hungary reported menstrual pain that limited their daily activity. After adjusting for age, body mass and other confounding factors, effort–reward imbalance and work over-commitment were significantly associated with increased risk of dysmenorrhoea (odds ratios 1.42 and 1.07 respectively). Although possible explanations are advanced, future research would need to determine if the relationship is causal.

Journal of Occupational and Environmental Medicine 2009; 51(2): 157–163.

Absence predicts mortality

Risk of future mortality increases the more sickness absence a worker takes, according to study of nearly 236,000 Danish workers in receipt of statutory sickness absence compensation. Individual absence duration was recorded over 12 months, with mortality monitored over four years, starting two years after the end of the absence-recording period. Just over 3,000 workers (1.3%) died during the follow-up. Age-adjusted mortality rate in men with one week’s absence was 2.53 deaths per 1,000 person years; each additional week’s absence was associated with a higher mortality rate, rising to 5.18 per 1,000 at six or more weeks. Sickness absence duration, which was also predictive of female mortality, may thus be useful to inform secondary prevention measures.

Occupational and Environmental Medicine 2009; 66: 150–153.