Rheumatoid arthritis greatly increases the risk of both deep vein thrombosis and pulmonary embolism.

The debilitating effects of rheumatoid arthritis, an inflammatory autoimmune disease, appear to be even more serious than once thought, according to new findings from a population-based study in Taiwan.

Researchers found that the disease greatly increases the risk of deep vein thrombosis (DVT) and pulmonary embolism (PE), which are blood clots in the veins of the legs and lungs, respectively. On its own, rheumatoid arthritis already carries serious health concerns, including severe joint pain and muscle atrophy.

For the study, researchers in Taiwan used information from nearly 30,000 patients in Taiwan’s National Health Insurance Research Database gathered between 1998 and 2008. The patients with rheumatoid arthritis (RA) were compared to healthy people in the general population of the same age and gender.

An analysis of the data showed that for those patients with RA, the risk of developing DVT was over three times as high compared to the health control group. The risk of developing PE was just over two times as high.

The researchers also discovered that RA patients with other diseases also faced a high risk of developing these blood clotting disorders. According to the study authors, “patients with RA had a higher prevalence of pre-existing comorbidities in hypertension, diabetes, hyperlipidaemia, heart failure, and lower leg fracture or surgery,” meaning that the disease has the potential to attack the body in far more ways than one.

RA generally affects older people. That trend held true in the Taiwanese study, with about a fifth of the patients with RA older than 65. More than three-quarters of the patients affected were women, who typically outnumber male RA patients.

However, the data show that RA is a critical issue even for the young. Some of the hardest hit patients were under 50, with their risks for DVP and PE eclipsing even their older peers by sixfold and threefold respectively.

“These findings highlight the importance of a multidisciplinary team adopting an integrated approach to the intervention of potential risk factors among patients with RA,” the study authors wrote. “Future research concerning RA severity scale, such as disease activity, functional impairment, and physical damage are warranted.”

As alarming as these results may be, the researchers say that more study of the risks associated with rheumatoid arthritis, especially DVT and PE, is the next best step forward.