Background People with chronic obstructive pulmonary disease (COPD) are at increased risk of vascular disease, including venous thromboembolism (VTE).1 While some researchers have tested the hypothesis that within COPD certain subgroups of patients, in particular frequent exacerbators, are at even greater risk of cardiovascular disease, no large-scale investigations of the relationship between exacerbation frequency or disease severity and VTE risk have been undertaken.
Methods 3,594 COPD patients recording a first VTE event during the period 1 January 2004 to 31 December 2013 were identified from the Clinical Practice Research Datalink (CPRD GOLD) dataset (cases) and matched (1:3) on age, sex and GP practice to 10,782 VTE-free COPD patients (controls). COPD severity was categorised by degree of airflow limitation (i.e. GOLD stage) and by COPD medication history (very severe, severe, moderate/mild). Patients were classed as “frequent exacerbators” if they experienced ≥ 2 exacerbations per year and as “infrequent exacerbators” otherwise. Analyses were conducted in STATA using conditional logistic regression to account for the study design.
Results After controlling for smoking and BMI, as well as the matching variables, there was an association between increased disease severity and VTE when severity was measured in terms of lung function impairment (ORmoderate/mild = 1.16; 95% CIs: 1.03, 1.32; p = 0.018) and also in terms of medication history (ORsevere/moderate+mild = 1.17; 95% CIs: 1.06, 1.26; p = 0.001). There was no evidence to suggest that that frequent exacerbators were at greater risk of VTE than infrequent exacerbators (OR = 1.06; 95%: CIs 0.97, 1.15; p = 0.18).
Conclusion Severity of disease but not frequent exacerbation appears to be associated with VTE events in COPD patients.