Work in Brief

Keith Palmer Editor

Balance of evidence reviews suggest that shift workers are at higher risk of ischaemic heart disease. However, results from individual studies have not been wholly consistent, a variation that could be explained by bias or confounding. Investigation is hampered by potential healthy hire and survivor effects. Yadegarfar and McNamee have conducted a case-referent study nested within a male industrial cohort from the nuclear fuel industry.¹ Over 600 cases who died from ischaemic heart disease were matched on age and year of hire with surviving controls, with focus on events 10 years after hire. Adjustment was made for several risk factors such as blood pressure and smoking, social class, duration of employment and time since leaving employment. Shift workers more often belonged to social class IV or V and some evidence was found for confounding by social class. In the fully adjusted model, however, the odds ratio for shift versus day work was close to unity, with no dose–response relation.

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Multi-disciplinary active-orientated inpatient rehabilitation has been adopted for chronic back or neck pain in the national rehabilitation programmes of many countries. Suoyrjö et al have investigated the effectiveness of the Finnish rehabilitation regime in a cohort of nearly 35 000 government employees.² At baseline, annual rates of sickness absence exceeding 21 days were three times more common in chronic back pain rehabilitees than in non-rehabilitees; 3 years after rehabilitation the ratio declined to 1.9 but no further reduction was found over a further 5 years of follow-up. By contrast, the rehabilitation programme had little impact on the sickness absence of rehabilitees with chronic neck pain, although reducing analgesic consumption both in this group and in back pain sufferers.

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Poor mental health shows a socio-economic gradient, with a predilection for the socially disadvantaged. But investigations of the phenomenon have mixed unemployed and economically inactive subjects with workers and the relative contribution of work and non-work risk factors remains unclear. Virtanen et al have teased out the relations in a representative sample of the Finnish working population (the Health 2000 Study).³ Depressive or anxiety disorder was 2–3 times more common in low-income groups than in high-income groups. In men, work factors explained more of the association than non-work factors (31% vs 21%) but in women, non-worker factors predominated (65% vs 23%). The gradient observed across the population as a whole holds true also for workers but there are important gender differences in the pattern of associated risk factors.

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This month’s Journal also includes an investigation of sickness absence based on the influential Whitehall II cohort,⁴ a time-to-pregnancy study in male greenhouse workers with exposure to pesticides⁵ and a report on whether cold modifies the cardiovascular mortality risks of particulate air pollution.⁶

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1.	Yadegarfar G, McNamee R. Shift work, confounding and death from ischaemic heart disease. Occup Environ Med 2008; 65: 158–63.[Abstract/Free Full Text]
2.	Suoyrijö H, Hinkka K, Oksanen T, et al. Effects of multidisciplinary inpatient rehabilitation for chronic back or neck pain: a register-linkage study of sickness absences and analgesic purchases in an occupational cohort. Occup Environ Med 2008; 65: 179–84.[Abstract/Free Full Text]
3.	Virtanen M, Koskinen S, Kivimäki M, et al. Contribution of non-work and work-related risk factors to the association between income and mental disorders in a working population: the Health 2000 Study. Occup Environ Med 2008; 65: 171–8.[Abstract/Free Full Text]
4.	Kivimäki M, Ferrie J E, Shipley M J, et al. Low medically certified sickness absence among employees with poor health status predicts future health improvement: the Whitehall II study. Occup Environ Med 2008; 65: 208–210.[Abstract/Free Full Text]
5.	Bretveld R, Kik S, Hooiveld M, et al. Time-to-pregnancy among male greenhouse workers. Occup Environ Med 2008; 65: 185–90.[Abstract/Free Full Text]
6.	Carder M, McNamee R, Beverland I, et al. Interacting effects of particulate pollution and cold temperature on cardiorespiratory mortality in Scotland. Occup Environ Med 2008; 65: 197–204.[Abstract/Free Full Text]

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