Inflammation markers and their trajectories after deep vein thrombosis in relation to risk of post‐thrombotic syndrome

BACKGROUND: Post-thrombotic syndrome (PTS) is a frequent chronic complication of deep vein thrombosis (DVT). OBJECTIVE: In the BioSOX study, we investigated whether inflammation markers predict the risk of PTS after DVT. METHODS: We measured C-reactive protein (CRP), ICAM-1, interleukin (IL)-6, and IL-10, at baseline, and 1 month and 6 months after a first proximal DVT, among 803 participants in the SOX trial. Participants were prospectively followed for 24 months for development of PTS. RESULTS: Median CRP levels at 1 month, ICAM-1 levels at baseline, 1 month and 6 months, IL-6 levels at 1 month and 6 months and IL-10 levels at 6 months were higher in patients who developed PTS than in those who did not. Multivariable regression with the median as a cutoff showed risk ratios (RRs) for PTS of 1.23 (95% confidence interval [CI] 1.05-1.45) and 1.25 (95% CI 1.05-1.48) for ICAM-1 at 1 month and 6 months, respectively, and 1.27 (95% CI 1.07-1.51) for IL-10 at 6 months. Quartile-based analysis demonstrated a dose-response association between ICAM-1 and PTS. ICAM-1 and IL-10 were also associated with PTS severity. Analysis of biomarker trajectories after DVT demonstrated an association between the highest-trajectory group of ICAM-1 and PTS. CONCLUSIONS: In this prospective study, ICAM-1 over time was most consistently associated with the risk of PTS. Further study is required to confirm these findings and assess their potential clinical relevance.