Asthma–Chronic Obstructive Pulmonary Disease Overlap Syndrome Associated with Risk of Pulmonary Embolism

PURPOSE: We conducted a cohort study to clarify this relationship between asthma–chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) and pulmonary embolism (PE). METHODS: From the National Health Insurance Research Database of Taiwan, we identified patients who had a diagnosis of asthma and a diagnosis of COPD (defined as ACOS) and concurrent treatment between January 1999 and December 2009 (ACOS cohort: n = 14,150; non-ACOS cohort: n = 55,876). Cox proportional hazards regression analysis was performed to determine the adjusted hazard ratios (aHRs) for PE of the ACOS cohort compared with the non-ACOS cohort. RESULTS: Comparing the ACOS cohort with the non-ACOS cohort, the aHR of PE was 2.08 (95% confidence intervals [CIs]: 1.56–2.76). The risk of PE was higher in ACOS cohort than non-ACOS cohort, regardless of age, sex, comorbidity, inhaled corticosteroids (ICSs) and oral steroids (OSs) used. For ages ranging from 20 to 65 years, the aHR of PE was 2.53 (95% CI: 1.44–4.44) in the ACOS cohort. ACOS patients using ICSs (aHR: 1.97, 95% CI: 1.29–3.01) or OSs (aHR: 1.97, 95% CI: 1.46–2.65), the risk of PE was higher than in the non-ACOS cohort. The risk of PE increased with the number of outpatient visits and hospitalizations necessitated, ranging from 2.32 (95% CI: 1.54–3.52) in patients having 3–9 visits to 4.20 (95% CI: 2.74–6.44) for those having >9 visits. CONCLUSIONS: ACOS is associated with increased risk of PE, particularly patients with a high frequency of AE—even in young adults or people without comorbidities.