According to a report published Online First by The Lancet, individuals admitted to hospital for an autoimmune disorder have a significantly higher risk of experiencing a pulmonary embolism during the next 12 months. Therefore prophylaxis may be permitted in these individuals. The article was written by Dr Bengt Zöller, Center for Primary Health Care Research, Lund University and Clinical Research Centre, Malmo University Hospital, Sweden, and colleagues.

Venous thromboembolism is a major health problem, for which pulmonary embolism is a potentially life threatening complication. Pulmonary embolism is a prevalent cardiovascular and cardiopulmonary disease. Each year in the U.S. more than 1 in 1,000 individuals are affected by the illness, which has a morality rate of over 15% in the first three months after diagnosis, similar to the mortality rate for acute myocardial infarction (heart attack). Inflammation is associated with venous thromboembolism, with inflammation powering venous thrombosis (deep vein thrombosis).

The investigation examined over 500,000 individuals who were admitted to hospital for any of 33 autoimmune disorders between 1964 – 2008 in Sweden. The three most prevalent autoimmune disorders were:

Other autoimmune disorders include Crohn’s disease, psoriasis, and chronic rheumatic heart disease.

The researchers report that the overall risk of pulmonary embolism during the first year following hospital admission for an autoimmune disorder was six times higher than individuals without an autoimmune disorder.

All 33 of the autoimmune disorders were connected with a considerably increased risk of patients experiencing pulmonary embolism during the first year after admission. The team found that this overall risk was comparable to the increased risk of Grave’s disease and rheumatoid arthritis.

Compared to individuals without an autoimmune disorder, some conditions had a significantly increased risk of pulmonary embolism:

  • Polymyositis or dermatomyositis – 16 times increased risk
  • Polyarteritis nodosa – 13 times increased risk
  • Immune thrombocytopenic purpura – 11 times increased risk

Over time, overall risk decreased from the six times increased risk within one year as mentioned above, to a 50% higher risk at 1-5 years, to a 15% higher risk at 5-10 years and a 4% increased risk at 10+ years. The risk increased for both men and women and all age groups.

The researchers state that the increased risk of venous thromboembolism may have alternative underlying causes in different autoimmune disease, and may reveal more severe cases of these types of disorders, as individuals in this investigation had been hospitalized.

The researchers explain:

“Our results show that autoimmune disorders affect the risk of hospital admission for pulmonary embolism in men and women of all ages 33 autoimmune diseases were associated with significantly increased risks of pulmonary embolism during the first year after admission.

Our findings show that autoimmune disorders in general should be regarded not only as inflammatory disorders, but also a hypercoagulable (blood clotting) disorders. Prophylaxis could be warranted in patients admitted with autoimmune disorders or at least for those disorders for which the risk of pulmonary embolism was very high. Further studies are needed to assess the potential usefulness of such treatment.”

In a joint comment, Dr. Carani B Sanjeevi, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden, stated:

“The decrease in overall risk for pulmonary embolism over time for all 33 autoimmune diseases suggests that the decrease in inflammation could be due to reductions in inflammatory activity and treatment. Nevertheless, a clear link is shown between thrombosis and inflammation.

Anti-inflammatory drugs and thromboprophylaxis should be considered to treat inflammation associated with autoimmune disorders, particularly in those admitted to hospital. However, prospective studies are needed to identify the predictive value of inflammatory markers for pulmonary embolism.”

Written by Grace Rattue