ROANOKE TIMES
Copyright (c) 1995, Roanoke Times
DATE: Friday, December 1, 1995 TAG: 9512010046
SECTION: NATIONAL/INTERNATIONAL PAGE: A-9 EDITION: METRO
DATELINE: DALLAS
SOURCE: Associated Press
NURSES WERE FOUND to be 70 percent more likely to have heart attacks after six years on irregular shifts.
Working rotating shifts may be hazardous to women's hearts, a study suggests.
The study, in today's issue of the American Heart Association journal Circulation, says women nurses who worked irregular shifts for more than six years were up to 70 percent more likely than co-workers to suffer a heart attack.
The study was done by a team at the Harvard Medical School and written by Dr. Ichiro Kawachi, an assistant professor of medicine.
``Shift work is a type of stress,'' he said. ``If you disrupt the body's daily biological clock, the body responds by pouring out stress-related hormones ... and these things generally do bad things for the body.''
Kawachi said ``rotating night shifts also are associated with reduced job-related performance and higher levels of perceived stress.''
The study focused on nursing because it is one of the few professions in which a large number of women work night shifts.
In 1976, the Harvard team began tracking more than 121,000 female nurses, ages 30 to 55, who were free of diagnosed heart disease or stroke. In 1988, researchers asked them how many years they had worked rotating night shifts, which was defined as at least three night shifts each month in addition to day and evening shifts.
Of the 79,000 nurses who responded, about 59 percent had done shift work and 41 percent had not.
From 1988 to 1992, 292 of the respondents had heart attacks, 44 of which were fatal.
``After adjusting for cigarette smoking and a number of other risk factors, such as whether they had hypertension, whether they were overweight or had high cholesterol, whether they drank alcohol, etc., we found a moderately increased - up to 70 percent higher - risk of heart attack among women who had worked rotating shifts six years or more,'' Kawachi said.
The overall risk of a heart attack was low for the entire group; for that reason, the 70 percent figure was considered a moderately higher risk.
The risk was highest among women who were still working rotating shifts; it dropped to 50 percent when women no longer doing shift work were added in - implying ``that when you stop doing shift work, the risk might come down somewhat,'' Kawachi said.
The study appears to corroborate an earlier study of male paper mill workers in Sweden. Published in the British medical journal The Lancet in 1986, that study showed an 80 percent increase in risk of cardiovascular disease among shift workers compared with day workers.
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