Heart Disease:

 

Heart Disease:

By ELAINE ST. PETER

Heart disease is the leading cause of death in the United States. In a new study
from Brigham and Women’s Hospital and Harvard Medical School published in the April
26 issue of JAMA, researchers found that women who work more than 10 years of
rotating night shift work had a 15 to 18 percent increased risk of developing
coronary heart disease, the most common type of heart disease, as compared with
women who did not work rotating night shifts.

“There are a number of known risk factors for coronary heart disease, such as
smoking, poor diet, lack of physical activity and elevated body mass index. These
are all critical factors when thinking how to prevent coronary heart disease.
However, even after controlling for these risk factors, we still saw an increased
risk of coronary heart disease associated with rotating shift work,” said lead
author Celine Vetter, an HMS instructor in medicine and a chronobiologist at Brigham
and Women’s. “Even though the absolute risk is small and the contribution of shift
work to coronary heart disease is modest, it is important to note that this is a
modifiable risk factor, and changing shift schedules may have an impact on the
prevention of coronary heart disease.”

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Researchers examined the association between rotating night shift work and coronary
heart disease over a period of 24 years. About 189,000 women in the Nurses’ Health
Study I and II who reported their lifetime exposure to rotating night shift work
(defined as three or more night shifts per month, in addition to day and evening
shifts) in 1988 and 1989 were included in the analysis.

These women also reported on their coronary health, indicating whether they had an
angiogram that confirmed coronary heart disease-related chest pain, a heart attack
or cardiovascular procedures such as angioplasty, coronary artery bypass graft
surgery or stents. 

In the case of a self-reported heart attack, or death, information was confirmed by
medical records and death certificates to ensure that the event was related to
coronary heart disease.

Questionnaires also collected data on known risk factors of coronary heart disease
every two to four years throughout the study period. Over the 24-year period, more
than 10,000 newly developed cases of coronary heart disease occurred.

In addition, researchers also found that recent shift work might be most relevant
for coronary heart disease risk and that longer time since stopping shift work was
associated with decreased coronary heart disease risk, a new finding that
researchers note warrants replication.

“Our results are in line with other findings, yet it is possible that different
schedules might carry a different risk, and we have very little information on exact
schedules, as well as work start and end times,” said Vetter, who is also an
associate epidemiologist in the Channing Division of Network Medicine. “We believe
that the results from our study underline the need for future research to further
explore the relationship between shift schedules, individual characteristics and
coronary health to potentially reduce coronary heart disease risk.”

Researchers note that individual characteristics such as the individual’s biological
rhythm, disrupted in rotating night shift workers, and information on sleep patterns
and quality might modulate coronary heart disease risk.