Severe asthma greatly enhances the risk of pulmonary embolism, particularly if chronic corticosteroids are used, according to study results published online ahead of print in the European Respiratory Journal .

For the study, 283 patients with severe asthma and 365 with mild-moderate asthma completed a questionnaire about past diagnosis of deep-vein thrombosis (DVT) and pulmonary embolism (PE), as well as their risk factors, history of asthma and medication use.

In total, 35 venous thromboembolic events (VTE) events—19 pulmonary embolism (PE) and 16 deep-vein thrombosis (DVT)—occurred at a median age of 39 years. The incidence of PE in patients with severe asthma was 0.93 per 1000 person-years, 0.33 in mild-moderate asthma, and 0.18 in the general population, respectively. Severe asthma and oral corticosteroid use were independent risk factors of PE; however, asthma was not associated with DVT.

According to researchers, the results demonstrate that people with severe asthma were almost 9 times more at risk of pulmonary embolism, compared to the general population. In addition, people with mild-moderate asthma tended to have a 3.5-times increased risk of pulmonary embolism. The study also identified oral corticosteroids as a potential risk factor for pulmonary embolism.

“This is the first time a link has been found between asthma and pulmonary embolism and we believe these results have important clinical implications,” said lead author Christof J. Majoor, MD, from the Department of Respiratory Medicine, Academic Medical Centre, Amsterdam. “Our findings suggest that people with severe asthma have an increased risk of pulmonary embolism and doctors should increase their awareness of the possibility of this occurrence in order to help prevent this serious event.”