Background: The effects of antithrombin (AT), protein C (PC) and protein S (PS) on the pathogenesis of portal vein thrombosis (PVT) in liver cirrhosis remain controversial in different studies. In this study, a systematic review and meta-analysis to examine this issue were performed.
Methods: PubMed database was employed to identify all studies in which AT, PC and PS concentrations were measured in both cirrhotic patients with and without PVT. A standardized mean difference (SMD) with 95% confidence interval (CI) was calculated to evaluate the effect of AT, PC and PS on PVT. Data were pooled using both fixed-effect and random-effect models. Only the pooled data using random-effect model were considered appropriate, when significant heterogeneity was observed.
Results: Nine studies involving 160 cirrhotic patients with PVT and 428 cirrhotic patients without PVT were eligible. AT and PC concentrations were similar between PVT and non-PVT groups (AT: SMD = -0.21, 95% CI = -0.56 to 0.14, P = 0.24; PC: SMD = -0.23, 95% CI = -0.55 to 0.09, P = 0.16). But PS concentration was significantly lower in the PVT group than in the non-PVT group (SMD = -0.29, 95% CI = -0.49 to -0.08, P = 0.006). Subgroup analyses were further conducted in 4 studies in which baseline liver function was similar between cirrhotic patients with and without PVT, showing similar AT, PC and PS concentrations between the 2 groups (AT: SMD = -0.10, 95% CI = -0.36 to 0.16, P = 0.57; PC: SMD = -0.18, 95% CI = -0.62 to 0.25, P = 0.41; PS: SMD = -0.10, 95% CI = -0.59 to 0.39, P = 0.69).
Conclusions: AT, PC and PS concentrations might not be associated with the pathogenesis of PVT in liver cirrhosis, especially when the impact of liver function was excluded.