Supernormal Antithrombin Activity Is an Independent Predictor of In-Hospital Mortality in Patients With Sepsis: A Retrospective Observational Study.

Supernormal antithrombin (AT) activity is rare in patients with sepsis. This study compared mortality rate of patients with sepsis and supernormal AT activity with that of other patients. This retrospective study included patients with sepsis from 42 intensive care units (ICUs) in Japan. Patients were included if their AT activity was measured on ICU admission, and if they did not receive AT concentrate. They were categorized into low, normal, and supernormal with respective AT activity of ≤70%, >70% to ≤100%, and >100%. The primary outcome was hospital in-patient mortality. Nonlinear regression analysis showed that mortality risk gradually increased with AT activity in the supernormal range, but without statistical significance. Survival rate was significantly lower in low (67%) and supernormal (57%) AT groups than in the normal AT group (79%; P < .001 and P = .008, respectively). After adjusting for disease severity and AT activity on day 2, supernormal AT activity was the only independent predictor of mortality. Sepsis with supernormal AT activity associated with high mortality, independent of disease severity, might be a predictor of in-hospital mortality.