Risk factors for work disability

A recent study has found that low levels of supportive leadership and monotonous work are the principal psychosocial predictors of work-related disability. Key mechanical factors identified were neck flexion, prolonged standing, whole-body vibration and heavy physical work. Disability rates were found to be higher among women, older workers, those with fewer years of education and those with higher levels of psychological distress and musculoskeletal complaints.

About the study

Working time lost because of sickness and disability is costly both for individual workers and for society.

In Norway, the disability rate is close to 10% of the working-age population (OECD, 2010), but disability rates vary considerably between occupations (Stattin and Jarvholm, 2005). Work-related psychosocial factors have been acknowledged as potential risk factors for occupational disability, along with work-related mechanical factors. Some earlier studies have argued that psychosocial factors may be confounded by mechanical exposures at work and vice versa (MacDonald et al, 2001; Bang Christensen et al, 2007).

The aim of a recent study, Work-related psychosocial and mechanical risk factors for work disability: A three-year follow-up study of the general working population in Norway (Sterud, 2013), was to identify work-related psychosocial and mechanical factors that contribute to the risk of work disability when potential confounders such as age, sex and education are taken into account.

Methodology

Data were provided from the nationwide study of living conditions–work environment conducted by Statistics Norway (SSB). A cohort aged 18–66 was drawn randomly from the general population in Norway and followed for three years (number of interviewees=12,550, 67% response rate at baseline).

Data were collected during two periods (18 September 2006–24 February 2007 and 22 June 2009–09 January 2010) by personal telephone interviews (0.5% of the completed interviews were face-to-face interviews). Eligible respondents were in paid work for 10 hours or more each week in 2006, and were either still in paid work or had quit working because of health problems (work disability) in 2009 (number=6,745). Five work-related psychosocial factors and eight mechanical exposures were measured. The outcome focused on by this three-year follow-up study was self-reported work disability.

Key findings

In total, 2.6% (176 individuals) were classified as having work disability at the time of the follow-up interviews (see table). Disability rates increased with age and the rate was higher among women (3.4%) than men (1.9%), among employees with lower levels of education (6% for those educated to basic school level) than among those with four or more years of university/college education (0.6%), as well as for those with higher levels of psychological distress and musculoskeletal complaints.

Note: 95% confidence interval (CI).

After adjusting for these factors, the odds ratios (OR) for work-related psychosocial predictors of disability were low levels of supportive leadership [OR: 1.61, 95% CI) 1.02–2.56] and monotonous work (OR: 1.53, 95% CI 1.09–2.16).

No mechanical factors acted as confounders related to any of the psychosocial factors. The odds ratios for work-related mechanical factors were neck flexion (OR: 2.49, 95% CI 1.36–4.56), prolonged standing (OR: 1.79, 95% CI 1.21–2.46), whole-body vibration (OR: 4.15, 95% CI 1.77–9.71), and heavy physical work (OR: 2.23. 95% CI 1.08–4.57). No psychosocial factors acted as confounders related to any of the mechanical factors.

The study provides evidence that monotonous work, prolonged standing, neck flexion and whole-body vibration appear to be the most consistent and important predictors of work disability. The estimated population risk attributable to these psychological and mechanical factors was about 45%.

References

Bang Christensen, K., Lund, T., Labriola, M., Villadsen, E. and Bultmann, U. (2007), ʻThe fraction of long-term sickness absence attributable to work environmental factors: Prospective results from the Danish Work Environment Cohort Study᾿, Occupational and Environmental Medicine, Vol. 64, No. 7, pp. 487–489.

MacDonald, L. A., Karasek, R. A., Punnett, L. and Scharf, T. (2001), ʻCovariation between workplace physical and psychosocial stressors: Evidence and implications for occupational health research and prevention᾿, Ergonomics, Vol. 44, No. 7, pp. 696–718.

OECD (2010), ‘Key trends and outcomes in sickness and disability’, in OECD, Sickness, disability and work: Breaking the barriers – A synthesis of findings across OECD countries, OECD Publishing, Paris.

Stattin, M. and Järvholm, B. (2005), ‘Occupation, work environment, and disability pension: A prospective study of construction workers’, Scandinavian Journal of Public Health, Vol. 33, No. 2, pp. 84–90.

Sterud, T (2013). ʻWork-related psychosocial and mechanical risk factors for work disability: A three-year follow-up study of the general working population in Norway’, Scandinavian Journal of Work and Environmental Health, online first.

Bjørn Tore Langeland, National Institute of Occupational Health