Impact of Common Iliac Vein Compression Degree on Incidence of Pulmonary Embolism in Patients with Acute Deep Vein Thrombosis.

OBJECTIVE: This study aimed to investigate the association between common iliac vein (CIV) compression and pulmonary embolism (PE) in lower extremity deep vein thrombosis (DVT).

METHODS: This was a single centre retrospective study. Between January 2016 and December 2021, DVT patients with enhanced computed tomography of the iliac vein and pulmonary artery were included. Patient demographics, comorbidities, risk factors, and CIV compression degree were collected and analysed. Logistic regression was performed to evaluate the odds ratio (OR) with a 95% confidence interval (CI) of PE in relation to compression severity groups. The association between PE and compression degree was evaluated with restricted cubic splines (RCS) based on an adjusted logistic regression model.

RESULTS: A total of 226 DVT patients (left side, n = 153; right side, n = 73) were included. Univariate analyses suggested that symptomatic or asymptomatic PE (54.4%, 123/226) was more common in men (p = .048) and right side DVT (p = .046) patients. Compared with no CIV compression, multivariable analyses suggested that mild compression did not statistically significantly reduce the PE risk, whereas moderate (adjusted OR 0.36; 95% CI 0.15 - 0.88; p = .025) and severe (adjusted OR 0.18; 95% CI 0.06 - 0.54; p = .002) compression statistically significantly reduced the risk. RCS showed that a smaller minimum diameter or greater compression percentage was correlated to continuously decreasing PE risk at levels of minimum diameter of < 6.77 mm or compression percentage of > 42.9%.

CONCLUSIONS: PE is more common in men and right side DVT patients. An increasing CIV compression severity is consistently associated with a decreasing risk for PE when the minimum diameter is < 6.77 mm or the compression percentage is > 42.9%, indicating that it is a protective factor against PE.