Splanchnic vein thrombosis (SVT) is a rare condition with a poorly understood prognosis.
We conducted a population-based cohort study (1994-2013), using data from Danish nationwide medical registries, to examine the short- and long-term prognosis of SVT. We identified 1915 incident cases of SVT and a matched comparison cohort of 18,267 persons without SVT (matched by cancer, cirrhosis, pancreatitis, alcohol-related disease, atrial fibrillation/flutter, venous thromboembolism, heart failure, and inflammatory bowel disease). We used the Kaplan-Meier method to calculate absolute risk of death. Using stratified Cox regression, we computed mortality rate ratios (MRRs) with 95% confidence intervals (CIs), comparing SVT patients with the comparison cohort.
We identified 1,500 (78%) patients with portal vein thrombosis, 204 (11%) with hepatic vein thrombosis, and 211 (11%) with mesenteric vein thrombosis. The mortality risks were markedly higher for SVT patients than for the comparison cohort during the first 5years of follow-up (30-day risk: 20.6% vs. 0.7%; 31-364-day risk: 21.7% vs. 4.7%; and 1-5-year risk: 25.4% vs. 17.7%). The corresponding MRRs were 40.7 (95% CI: 32.4-51.1), 7.4 (95% CI: 6.4-8.6), and 2.4 (95% CI: 2.1-2.8), respectively. The 30-day mortality was higher after mesenteric vein thrombosis than portal and hepatic vein thrombosis, whereas portal vein thrombosis had a stronger impact on mortality after 30days than hepatic and mesenteric vein thrombosis.
Splanchnic vein thrombosis has a poor short- and long-term prognosis that varies according to subtype of thrombosis. Reasons for the increased mortality in patients with SVT need further clarification.