To analyze the relationship between antithrombin Ⅲ(AT-Ⅲ) activity and survival, bleeding and thrombosis complications in patients with acute-on-chronic liver failure (ACLF), and to explore the prediction value of AT-Ⅲ activity in the prognosis of ACLF patients.

The clinical data of 130 hospitalized patients with ACLF were retrospectively collected in Wuxi No.5 People′s Hospital from January 1, 2013 to April 1, 2019. The liver function, international normalized ratio (INR), and 90-day survival rate were detected. The AT-Ⅲ activity values at admission, week two, week four, and week eight of hospitalization were recorded, and the occurrences of fecal occult blood and femoral vein thrombosis were also recorded. The measurement data were compared by t test, analysis of variance, or rank sum test, and the categorical data were compared by chi-square test. The risk factors affecting the survival of ACLF patients were analyzed by Cox regression. The survival analysis was performed using the Kaplan-Meier method.

At the end of 90-day follow-up of 130 patients, 56 patients died, 20 patients (15.38%) were fecal occult blood positive and 15 (11.54%) had femoral vein thrombosis. The baseline AT-Ⅲ activity in the death group was lower than that in the survival group ((17.89±13.68)% vs (36.03±11.96)%), and the difference was statistically significant (t=-8.045, P<0.01). The baseline AT-Ⅲ activities in fecal occult blood positive and negative patients were (18.26±11.52)% and (25.06±10.97)%, respectively, and in femoral vein thrombosis and non-thrombotic patients were (17.55±10.33)% and (32.48±11.88)%, respectively. The differences were both statistically significant (t=8.746 and 8.090, respectively, both P<0.01). Through dynamic monitoring of AT-Ⅲ, the AT-Ⅲ activity showed a downward trend in the death group, while that showed an upward trend in the survival group, but the differences were not statistically significant (F=0.282 and 0.401, respectively, both P>0.05). The Cox regression analysis suggested INR (odds ratio (OR)=1.364, 95% confidence interval (CI) 1.078-1.726, P=0.010) and AT-Ⅲ activity (OR=0.930, 95%CI 0.906-0.954, P<0.01) were the independent factors affecting the survival of patients with ACLF. The area under the receiver operator characteristic curve of the AT-Ⅲ activity for predicting 90-day survival outcome of the patient was 0.706 (95%CI 0.773-0.952, P<0.01), and the cut-off value was 25%. Patients with AT-Ⅲ activity ≥ 25% had a higher survival rate than those with AT-Ⅲ activity <25% (χ²=58.20, P<0.01).

AT-Ⅲ activity is associated with fecal occult blood positive and femoral vein thrombosis in ACLF patients. The AT-Ⅲ activity is an independent influencing factor for predicting the prognosis of ACLF patients. Patients with AT-Ⅲ activity less than 25% have the higher mortality rate.

Antithrombin Ⅲ, activity; Liver failure, acute-on-chronic; Prognosis; Forecasting