The triad of shift work, occupational noise, and physical workload and risk of coronary heart disease

Abstract

Background: Shift work, noise, and physical workload are very common occupational exposures and they tend to cluster in the same groups of workers. Objectives: To study the short and long term effects of these exposures on risk of coronary heart disease (CHD) and to estimate the joint effects of these factors. Methods: The study population in this prospective 13 year follow up study of 1804 middle aged industrially employed men was collected at the first screening for the Helsinki Heart Study. The CHD end points (ICD-9 codes 410-414 and ICD-10 codes I20-I25) were obtained from official Finnish registers. The Finnish job-exposure matrix FINJEM provided information on occupational exposures. Relative risks (RR) of CHD for the exposures were estimated using Cox's proportional hazard models adjusting for classical risk factors of CHD. Results: The RR in the five year follow up for continuous noise combined with impulse noise was 1.28; for shift work it was 1.59, and for physical workload 1.18, while in the 13 year follow up the RRs were 1.58, 1.34, and 1.31, respectively. When adjusted for white-collar/blue-collar status the RRs decreased markedly. The RR in the 13 year follow up for those exposed to two risk factors was close to 1.7 and for those exposed to all three, 1.87. Conclusion: Shift work and continuous noise entailed an excess risk for CHD in the shortest follow up with only a few retired workers but a decreasing risk during the longer follow up. For physical workload and impulse noise the trend was opposite: the CHD risk was increasing with increasing follow up time despite increasing numbers of retired workers.

Workhours in relation to work stress, recovery and health

“…A later cessation of shiftwork exposure decreases the risk. A recent 13-year follow-up study showed that the relative risk in the 5-year follow-up for shift work was 1.59, while in the 13-year follow-up with more retired workers, it decreased to 1.34 (54). There is also some evidence that night and shift work may have an impact on the metabolic syndrome (58,59) and type II diabetes (60).…”

“…Some prospective studies showing a relationship between shift work and CHD controlled for social class (52)(53)(54)(55)(56). A high demand-low control work situation, like that of effort-reward imbalance, may also partly mediate the association between shift work and cardiovascular risk; for example, the prevalence odds ratios for hypertension and atherogenic lipids attributable to effort-reward imbalance were relatively the highest among shift workers as compared with daytime workers (27).…”

“…There is evidence that shift work is an independent risk factor for CHD in relation to some physical work environment factors like noise and physical workload. In a recent follow-up study, the risk estimates for shift work varied from 1.62 to 1.22, depending on the length of the follow-up, the reference group, or adjusted factors (54).…”

“…According to a review of 13 longitudinal and 4 casereferent studies and a later meta-analysis including an additional negative study, shift work increases the risk of CHD by 30-40% even when other traditional risk factors and social class are controlled for (21,27,(51)(52)(53)(54)(55)(56)(57). A later cessation of shiftwork exposure decreases the risk.…”

Psychosomatic correlates of coronary heart disease during the socio-economic crisis of post-communist Bulgaria

“…The latter are often precursor events of coronary incidents [2,5,21,27]. The relation between stress / distress and acute myocardial infarction is a subject of many epidemiological studies, revealing that myocardial infarct can be easily triggered by external (environmental, social) factors, such as heavy physical and mental work load, violence etc [28][29][30][31][32].…”