SUNDAY, Jan. 9 (HealthDay News) -- People with immune-related disorders such as rheumatoid arthritis and lupus may be at increased risk for developing potentially deadly blood clots during hospital stays, a new study has found.

Researchers at the University of Oxford in the United Kingdom analyzed 45 years' worth of medical records of patients who were hospitalized for immune-related disorders and had no evidence or prior history of blood clots in a vein, also called venous thromboembolism (VTE) -- one type of which can break off and travel to block a blood vessel in the lungs.

The patients were divided into different groups based on their immune-related condition. The researchers then compared them to patients who were hospitalized for minor, non-immune-related problems such as broken bones and minor surgical procedures.

The findings are published in the current online edition of the journal BMC Medicine.

The investigators found significantly elevated rates of blood clots in the veins of people with certain immune diseases, particularly those with lupus and polyarteritis nodosa, a blood vessel disorder in which the arteries become swollen and damaged.

And while all patients who have surgery are at increased risk for blood clots, the risk seems to be even greater in patients with immune diseases, principal investigator Dr. Michael Goldacre said in a news release from the journal's publisher.

He and his colleagues suggested that inflammation caused by immune disorders may increase the tendency of blood to clot. If further research confirms this, these patients may benefit from anti-clotting drugs to protect them from blood clots while in the hospital, the study authors concluded.

More information

The U.S. Agency for Healthcare Research and Quality offers a guide to preventing and treating blood clots.