Chronic thromboembolic pulmonary hypertension (CTEPH) occurred frequently after pulmonary embolism but was less common after deep vein thrombosis (DVT), according to the results of a population-based cohort study published in Pulmonary Circulation.
Carlos Martinez, MD, of the Institute for Epidemiology, Statistics and Informatics GmbH in Frankfurt, Germany, and colleagues endeavored to determine the incidence and risk factors of CTEPH in a cohort of patients with a first venous thromboembolism (VTE) and no active cancer in England between 2001 and 2012. They determined the incidence of CTEPH using a rigorous case ascertainment algorithm and investigated CTEPH risk factors via a nested case-control method.
The investigators collected data from 23,329 patients with 81,413 person-years of follow-up and a mean follow-up of 3.5 years (maximum follow-up 11.0 years). A total of 283 patients were diagnosed with CTEPH for an incidence rate of 3.5 per 1000 person-years. The cumulative incidence of CTEPH was 1.3% and 3.3% at 2 years and 10 years after a pulmonary embolism, respectively. For DVT, the cumulative incidence was 0.3% and 1.3%, respectively.
The authors identified a number of risk factors associated with CTEPH, including >70 years of age (odds ratio [OR], 2.04), female gender (OR, 1.44), pulmonary embolism at first VTE (OR, 3.11), recurrent pulmonary embolism or DVT (OR, 3.17 and 2.46, respectively), chronic obstructive pulmonary disease (COPD; OR, 3.17), heart failure (OR, 2.52), splenectomy (OR, 4.30), and atrial fibrillation (OR, 2.42). Hypothyroidism was not associated with CTEPH. A sensitivity analysis showed an increased risk for systemic lupus erythematosus (OR, 3.66) and a decreased risk for asthma (OR, 0.60). The peak time for an occurrence of CTEPH was at 91 to 182 days after the first VTE.
The authors noted that pulmonary thrombosis is common in COPD and occurs most often in damaged sections of the lung, but it may be mistaken for an acute exacerbation of COPD. In atrial fibrillation, CTEPH is often associated with an atrial clot. The overall 2-year mortality from the time of CTEPH diagnosis was 26.8%.
Study limits included the potential for unmeasured confounding or hidden bias. As the onset of CTEPH is often subtle, the date of diagnosis does not reflect the actual onset of the condition.
The researchers argued that awareness of CTEPH risk factors may increase the rates of diagnosis, while referrals to specialized centers for confirmation of CTEPH and initiation of appropriate therapy may improve patient outcomes.
Martinez C, Wallenhorst C, Teal S, Cohen AT, Peacock AJ. Incidence and risk factors of chronic thromboembolic pulmonary hypertension following venous thromboembolism, a population-based cohort study in England [published online July 30, 2018]. Pulm Circ. doi:10.1177/2045894018791358