Prevalence and Localization of Pulmonary Embolism in Unexplained Acute Exacerbations of COPD: A Systematic Review and Meta-analysis.

BACKGROUND Patients with COPD experience episodes of increased inflammation, so-called acute exacerbations of COPD (AE-COPD). In 30% of AE-COPD cases, no clear cause is found. Since there is well-known cross talk between inflammation and thrombosis, the objectives of this study were to determine the prevalence, embolus localization, clinical relevance, and clinical markers of pulmonary embolism (PE) in unexplained AE-COPD. METHODS A systematic search was performed using MEDLINE and EMBASE platforms from 1974 to October 2015. Prospective and cross-sectional studies that included patients with AE-COPD and used pulmonary CT-angiography for diagnosis of PE were included. RESULTS The systematic search resulted in 1,650 records. The main reports of 22 articles were reviewed, and 7 studies were included. The pooled prevalence of PE in unexplained AE-COPD was 16.1% (95% CI, 8.3%-25.8%) in a total of 880 patients. Sixty-eight percent of the emboli found were located in the main pulmonary arteries, lobar arteries, or interlobar arteries. Mortality and length of hospital admission seemed to be increased in patients with unexplained AE-COPD and PE. Pleuritic chest pain and cardiac failure were more frequently reported in patients with unexplained AE-COPD and PE. In contrast, signs of respiratory tract infection was less frequently related to PE. CONCLUSIONS PE is frequently seen in unexplained AE-COPD. Two-thirds of emboli are found at locations that have a clear indication for anticoagulant treatment. These findings merit clinical attention. PE should receive increased awareness in patients with unexplained AE-COPD, especially when pleuritic chest pain and signs of cardiac failure are present, and no clear infectious origin can be identified.