Working outside 9-5 shifts vascular risk

Jul 31 2012

By Piriya Mahendra, MedWire Reporter

People who undertake shift work may be at a higher risk for vascular events than those who do not, researchers say in the BMJ.

Daniel Hackam (Stroke Prevention and Atherosclerosis Research Centre, Ontario, Canada) and co-researchers found that individuals who work outside of the typical 09:00-17:00 schedule (including evening, night, rotating, mixed, and irregular or unspecified schedules) may be putting themselves at an increased risk for vascular events.

The meta-analysis of 34 studies in 2,011,935 people found that individuals who undertook shift work had a 23% higher risk for myocardial infarction (MI) and a 5% higher risk for ischemic stroke than those who had a regular work schedule.

Shift workers also had a 24% higher risk for coronary events, defined as the composite of MI, coronary mortality, and hospital admissions due to coronary artery disease, albeit with significant heterogeneity across studies.

However, shift workers did not have an increased risk for mortality, whether vascular or otherwise, in relation to workers with regular schedules.

On the basis of the prevalence of adult shift workers in Canada, which in 2009-2010 stood at 32.8%, the population-attributable risks related to shift work were 7.0% for MI, 7.3% for coronary events, and 1.6% for ischemic stroke.

The meta-analysis recorded 6598 MIs, 17,359 coronary events, and 1854 ischemic strokes.

The authors say their findings show that the increased risk for vascular events among shift workers means that they should be vigilant about risk factor modification.

"Shift workers should be educated about cardiovascular symptoms in an effort to forestall or avert the earliest clinical manifestations of disease," they write.

Hackam and team add that the modification and rationalization of shift schedules may produce dividends "in terms of healthier, more productive workers," but concede that the long-term effect of these alterations on vascular outcomes is unknown.

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