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 Researchers who studied more than 6,600 women taking osteoporosis
drugs found that for nearly one in five, bone mineral density at the
hip actually decreased after the women started taking the
medication.
The hip “is an excellent site for monitoring bone mineral density
because it predicts fractures, can be measured with great
reliability making it easier to detect small changes, and is not
affected by age-related problems like spinal arthritis,” said lead
study author Dr. William Leslie, a radiology researcher at the
University of Manitoba.
The findings suggest it may be time for some physicians to rethink
their reluctance to get women bone mineral density tests after they
start medication, Leslie said.
Whether to send women for these tests - also called DEXA scans, for
dual-energy x-ray absorptiometry - once they start therapy “has been
controversial,” he added by email. “It is relatively inexpensive but
adds to the cost of care while there has been little scientific data
to answer the question of whether a change in bone mineral density
while receiving treatment tells us anything about that person’s
ongoing fracture risk.”
During menopause and afterward, the body slows production of new
bone tissue and women can face an increased risk of osteoporosis.
For the current study, researchers followed women for an average of
9.2 years starting when they were typically around 64 years old.
Most of the women were prescribed osteoporosis medicines known as
bisphosphonates, which work by slowing down how fast the body
removes old bone, allowing time to regrow bone and make fractures
less likely. This family of drugs includes Fosamax (alendronate
sodium), Actonel (risedronate sodium) and Boniva (ibandronate
sodium).
Overall, 910 women, or about 14 percent, experienced fractures
during the study period, including 198 with hip fractures,
researchers report in the Annals of Internal Medicine.
Bone mineral density tests of the hip showed that about 30 percent
of the women experienced an increase in density after they started
taking drugs and another 19 percent of these women had decreases.
Compared to women with similar hip bone mineral density before and
after starting osteoporosis drugs, the fracture risk for women with
a decrease in total hip bone mineral density was 2.9 percent higher
after five years and 5.5 percent higher after 10 years.
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In contrast, the risk of fractures was 1.3 percent lower at five
years and 2.6 percent lower at 10 years for women whose bone mineral
density increased during the study.
One limitation of the study is that women didn’t all wait the same
amount of time between their initial bone mineral density tests and
follow-up scans, the authors note.
The researchers, therefore, can’t say what the best retesting
regimen would be.
Because changes in bone mineral density occur fairly slowly in most
women, “there is some controversy as to what time point following an
initial baseline bone mineral density test should a repeat test be
performed,” said Dr. Matthew Drake, a researcher in radiology at the
Mayo Clinic College of Medicine in Rochester, Minnesota.
If the test is repeated too quickly, it may be hard to tell if any
measured change really represents bone loss, Drake, who wasn’t
involved in the study, said by email. Waiting at least two to three
years before a repeat test may be better for many patients, he said.
“There are several potential reasons why bone mineral density could
decrease after osteoporosis therapy is started,” Drake added. “These
include failing to continue taking the medication as directed; a
lack of adequate calcium and vitamin D intake,” or a decrease in
weight bearing activities.
SOURCE: http://bit.ly/1i46lF7 Annals of Internal Medicine, online
July 18, 2016.
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