RA May Increase Potential for Blood Clots
Researchers find tripled risk of leg blood clots, doubled odds of lung clots
By Kathleen Doheny
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 Diseases and 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 researchers found.
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.