Clinical course and treatment of incidentally detected splanchnic vein thrombosis: an individual patient data meta-analysis

Background: The clinical relevance and management of incidental splanchnic vein thrombosis (SVT) remain poorly defined. Objectives: The objectives of this study were to evaluate the clinical course of incidental SVT in comparison with symptomatic SVT and assess the safety and effectiveness of anticoagulant treatment in incidental SVT. Methods: Individual patient data meta-analysis of randomized controlled trials or prospective studies published up to June 2021. Efficacy outcomes were recurrent venous thromboembolism (VTE) and all-cause mortality. The safety outcome was major bleeding. Incidence rate ratios and 95% CIs for incidental vs symptomatic SVT were estimated before and after propensity-score matching. Multivariable Cox models were used considering anticoagulant treatment as a time-varying covariate. Results: In total, 493 patients with incidental SVT and 493 propensity-matched patients with symptomatic SVT were analyzed. Patients with incidental SVT were less likely to receive anticoagulant treatment (72.4% vs 83.6%). Incidence rate ratios (95% CI) for major bleeding, recurrent VTE, and all-cause mortality in patients with incidental SVT compared with symptomatic SVT were 1.3 (0.8, 2.2), 2.0 (1.2, 3.3), and 0.5 (0.4, 0.7), respectively. In patients with incidental SVT, anticoagulant therapy was associated with a lower risk of major bleeding (hazard ratio [HR] 0.41; 95% CI, 0.21 to 0.71), recurrent VTE (HR 0.33; 95% CI, 0.18 to 0.61), and all-cause mortality (HR 0.23; 95% CI, 0.15 to 0.35). Conclusion: Patients with incidental SVT appeared to have a similar risk of major bleeding, a higher risk of recurrent thrombosis, but lower all-cause mortality than patients with symptomatic SVT. Anticoagulant therapy seemed safe and effective in patients with incidental SVT.