Increasing evidence suggests that patients with asthma have activated coagulation within the airways. Whether this leads to an increase in venous thromboembolic events (VTE) is unknown. We therefore assessed the incidence of VTE in patients with mild-moderate and severe asthma as compared to an age- and gender-matched reference population.
648 patients with asthma (283 with severe and 365 patients with mild-moderate asthma) visiting 3 Dutch outpatient asthma clinics were studied. All patients completed a questionnaire about a diagnosis of deep-vein thrombosis (DVT) and pulmonary embolism (PE) in the past, their risk factors, history of asthma and medication use. All VTE were objectively verified.
In total, 35 VTE events (16 DVT and 19 PE) occurred at a median age of 39 (range 20–63) years. The incidence of PE in patients with severe asthma was 0.93 (95% Confidence Interval (CI): 0.42–1.44) per 1000 person-years, 0.33 (95%CI: 0.07–0.60) in mild-moderate asthma, and 0.18 (95%CI: 0.03–0.33) in the general population, respectively. Severe asthma and oral corticosteroid use were independent risk factors of PE (hazard ratios: 3.33 (1.16–9.93) and 2.82 (1.09–7.30), respectively). Asthma was not associated with DVT.
Severe asthma greatly enhances the risk of pulmonary embolism, particularly if chronic corticosteroids are used.