THURSDAY, Aug. 8 (HealthDay News) -- Rheumatoid arthritis
increases the risk of developing potentially fatal blood clots in
the legs and lungs, according to new research from Taiwan.
People with this inflammatory form of arthritis are more than
three times as likely to develop a deep vein thrombosis (a clot
usually in the legs) and twice as likely to have a pulmonary
thromboembolism (a clot that travels to the lungs) compared to
those without the diagnosis, the new study found.
"I would call this a moderate increased risk," said Dr. Tore Kvien, editor-in-chief of the journal Annals of the Rheumatic Diseasesand head of rheumatology at Diakonhjemmet Hospital in Oslo, Norway.
The research was published online Aug. 7 in the journal.
The study -- which found an association between rheumatoid
arthritis and blood clots, but not a direct cause-and-effect
relationship -- is the latest of several examining this link.
"This study is consistent with what our study and other published papers found," said Dr. Seoyoung Kim, assistant professor of medicine at Brigham and Women's Hospital and Harvard Medical School in Boston. In her study, Kim and her colleagues also reported an increased risk of blood clots in rheumatoid arthritis patients.
In the new study, the researchers used a national database to
identify about 30,000 people who developed rheumatoid arthritis
from 1998 to 2008. They monitored them through 2010 to see if the
rheumatoid arthritis diagnosis affected blood clot risk.
The researchers compared the data with records for 117,000
people without rheumatoid arthritis of the same age and sex.
Even after taking into account other health conditions such as
high blood pressure, surgery and cancer, those with rheumatoid
arthritis were still more likely to develop the blood clots than
those not diagnosed with rheumatoid arthritis.
Patients younger than 50 were especially vulnerable, the
About 1.3 million people in the United States -- about 0.4
percent of the population -- have rheumatoid arthritis, according
to the Arthritis Foundation. In rheumatoid arthritis, the immune
system attacks the body's own tissues, especially the thin membrane
lining the joints. This results in chronic pain and inflammation.
The cause is unknown, but experts believe genetic and environmental
factors are involved.
Besides being aware of the link with clots, Kvien suggested that
those with rheumatoid arthritis be as physically active as
The researchers can't fully explain their findings, but it is
thought that chronic inflammation plays a role.
The increased risk may be associated with inflammation, said
Kim, or with the rheumatoid arthritis treatments.
Patients with rheumatoid arthritis who need surgery, cancer
treatment or hospitalization should be placed on a clot-prevention
regimen, she said. People with the disease also should try to live
a healthy lifestyle to minimize the likelihood of clots.
"At this point, patients with RA should do their best to avoid modifiable risk factors for blood clots," said Dr. Diane Horowitz, a rheumatologist at North Shore University Hospital in Manhasset, N.Y., and Long Island Jewish Medical Center in New Hyde Park, N.Y. That means not smoking and avoiding prolonged periods of immobility, said Horowitz, who was not involved in the study.
Anyone with rheumatoid arthritis who has had a blood clot should
discuss the new findings with their rheumatologist, Horowitz
To determine whether the higher risk of clots can be reduced by
medication, physical activity, weight loss or not smoking, more
research is needed, Kim added.
To learn more about rheumatoid arthritis, visit the