Diabetes and Other Autoimmune Diseases Linked to Increased Risk of Blood Clots in Lungs

According to a nationwide review of data from the in-patient register, 31 of the 33 autoimmune diseases studied were associated with an increased risk of pulmonary embolism (a blood clot on the lung), including type 1 diabetes.

Autoimmune diseases—such as type 1 diabetes, thyroid diseases, rheumatoid arthritis, psoriasis and inflammatory bowel disease—cause elevated inflammation in tissue, which can, in certain cases, lead to an increased risk of clots in the veins.

The principal investigator of the study, Associate Professor Bengt Zöller, carried out the research at the Centre for Primary Health Care Research in Malmö, Sweden. According to Zöller, “the most dangerous complication of a blood clot is a blood clot on the lung.”

The study focused on data from 535,000 patients who had been admitted to hospital for 33 different autoimmune diseases. The researchers compared the risk these individuals suffered of a blood clot on the lung with the risk for non-autoimmune patients who had been admitted to a hospital.

After the findings were adjusted for other diseases, age, and socioeconomic factors, the researched showed that 31 of the 33 autoimmune diseases were linked to an increased risk of a blood clot on the lung.

“The risk was particularly high in the first year — around six times higher on average in all the groups with autoimmune diseases compared with the control group. For some of the diseases, the risk was even higher in the first year,” reported Bengt Zöller.

Type 1 diabetes in particular showed a whopping six-fold increase in the risk of a blood clot on the lung in the first year immediately after treatment at the hospital. Other diseases, such as idiopathic thrombocytopenic purpura, systemic lupus erythematosus (SLE), polymyositis, dermatomyositis, and polyarteritis nodosa, were found to have at least a ten-fold risk increase; rheumatoid arthritis was linked to a seven-fold increase.

There was an association with the passage of time and a decrease in the risk, however. “The risk of a blood clot fell with time,” stated Bengt Zöller. “It was still around 50%t higher after 1—5 years, yet there remained an increased risk for up to ten years after the first admission to hospital for many autoimmune conditions.”

This research could prove to be useful in preventing blood clots in future autoimmune disease patients after being admitted to hospital. “Further controlled studies are needed to determine the effect of preventive treatment”, said Bengt Zöller.

This study was published online in the Lancet journal online under the title “Risk of Pulmonary Embolism in Patients with Autoimmune Disorders: a nationwide follow-up study from Sweden”.