From a recent systematic review and meta-analysis:
Background COPD patients encounter episodes of increased inflammation, so-called acute exacerbations of COPD (AE-COPD). In 30% of AE-COPD no clear etiology is found. Since there is a well-known crosstalk between inflammation and thrombosis, the objectives of this study were to determine the prevalence, embolus localization and 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 – October 2015. Prospective- and cross-sectional studies that included patients with an AE-COPD and used pulmonary CT-angiography for diagnosis of PE were included.
Results The systematic search resulted in 1650 records. 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% confidence-interval 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 inter-lobar arteries. Mortality and length of hospital admission seem 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 localizations 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.
The mechanism of the association, as pointed out in the abstract above, may be the association between inflammation and thrombosis.
Other factors were mentioned as possible mechanisms for the association, as pointed out in a review of the paper by ACP Hospitalist Weekly.
This is not the first time such an association has been mentioned, and I have blogged about it several times in the past including here.