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Bob Schwadron
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EARTHQUAKES SHAKE, RATTLE AND RAISE BLOOD PRESSURE
Kobe Earthquake Provides Unprecedented Opportunity
For Researchers To Study Stress Effects On Hypertension
NEW YORK, N.Y. -- A natural disaster increases blood pressure
in patients with high blood pressure, medical researchers confirmed in a
landmark study published in the current issue of the American Journal of
Hypertension.
The Hanshin-Awaji earthquake that struck Kobe, Japan, on Jan.
17, 1995 at approximately 5:46 a.m., gave medical researchers the
unique opportunity to study the effects of environmental factors and
physical and mental stress on blood pressure. The earthquake,
measuring 7.2 on the Richter scale, killed more than 5,000 people, injured
more than 40,000 and left 320,000 homeless.
Kobe University School of Medicine researchers were able to
track 221 of their hypertensive patients. For the first time researchers
were able to study the short-term and long-term effects of a
life-threatening natural disaster on blood pressure control in patients
being treated with hypertension medications.
They found that 105 patients living closest to the epicenter of the
earthquake had a significant increase in blood pressure (approximately 7
mm Hg) during the first week when 5-to-20 aftershocks a day were
recorded. Mean blood pressure declined and returned to pre-earthquake
levels after six weeks. There was no significant change in mean blood
pressure in a group of 116 hypertensive patients living in the surrounding
area during the same time periods.
"The apparent contrast of the exposure-related blood pressure
response between the two groups can undoubtedly be explained by the
differences of severity of the earthquake with the resultant differences
in the majority of emotional stresses," the authors note. "The fact that
more than one-third of the exposed subjects became homeless and went
to shelters indicates that the disaster had a more pronounced impact on
the exposed than the nonexposed group."
The authors said although they did not have exact information,
psychosocial stresses such as death in the family, physical illness, and
loss of property and jobs were likely to be more serious in the exposed
group. They note that the numerous aftershocks may have caused
sleeplessness due to anxiety and fear.
The authors of the study, "The Great Hanshin-Awaji Earthquake
Aggravates Blood Pressure Control in Treated Hypertensive Patients,"
also found that the percent increase in mean blood pressure of 32
patients taking beta blockers was significantly smaller when compared
with the 73 patients treated with other types of antihypertensive
medications.
In a related study, also published in the February issue of the
American Journal of Hypertension, another group of researchers
reported the effects of the earthquake on blood pressure measured at
home by 36 patients using home blood pressure monitoring devices.
They found that 16 patients living within 30 miles of the epicenter
of the earthquake recorded increases in home blood pressure of
approximately 11 mm Hg during the first week following the disaster.
Their blood pressure gradually returned to baseline within four weeks.
The researchers from Japan's National Cardiovascular Center
found that blood pressure of 20 patients who lived more than 30 miles
from the earthquake's epicenter did not change significantly.
"These studies indicate that severe stress can have important
short-term effects on blood pressure," comments Michael Weber, MD, an
editor of the American Journal of Hypertension. "Less dramatic
stresses, which may not be as newsworthy as an earthquake but
important in the lives of individual patients, could also impact blood
pressure.
"Further information would be helpful to physicians in
understanding whether life stresses can predictably influence blood
pressure and in allowing physicians to make appropriate evaluations and
treatment changes in their patients."
The American Society of Hypertension is the largest US
organization devoted exclusively to hypertension and related
cardiovascular diseases. The organization is committed to alerting
physicians, allied health professionals and the public about new medical
options, facts research findings and treatment choices designed to
reduce the risk of cardiovascular disease.
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CIRCLE THE DATE: May 27-31 for the Twelfth Annual
Meeting of the American Society of
Hypertension, San Francisco, CA
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