Reduced antithrombin III and in-hospital organ failure in hypertriglyceridemia-associated acute pancreatitis with elevated D-dimer: a retrospective cohort study

Background D-dimer is widely used to reflect coagulation and fibrinolytic activation in acute pancreatitis, but outcomes vary among patients with elevated D-dimer. Reduced antithrombin III (AT-III) may indicate diminished endogenous anticoagulant reserve during systemic coagulation activation. We assessed the association between reduced AT-III and organ failure during hospitalization among patients with hypertriglyceridemia-associated acute pancreatitis (HTG-AP) and elevated D-dimer. Methods This retrospective cohort study included hospitalized patients with HTG-AP from October 2020 to November 2025. D-dimer elevation was defined as > 0.55 mg/L FEU and AT-III reduction as < 75%, according to local laboratory reference ranges. The primary outcome was organ failure during hospitalization. Patients admitted in 2020–2023 and 2024–2025 were described as the earlier and later admission cohorts, respectively. Among patients with elevated D-dimer, binary logistic regression was used to evaluate the association between reduced AT-III and organ failure. The main model adjusted for age, sex, ln(D-dimer), ln(triglycerides), and ln(time from symptom onset to admission + 1). Results Of 959 patients with complete admission D-dimer and AT-III data, 79 (8.2%) had organ failure during hospitalization. Among 418 patients with elevated D-dimer, organ failure occurred in 44 of 151 patients (29.1%) with reduced AT-III and in 25 of 267 patients (9.4%) with preserved AT-III. After adjustment including continuous ln(D-dimer), reduced AT-III remained associated with organ failure (odds ratio [OR] 3.30, 95% confidence interval [CI] 1.86–5.85; P < 0.001). The corresponding observed event rates in the earlier and later admission cohorts were 27.8% and 31.5% with reduced AT-III, compared with 9.5% and 9.2% with preserved AT-III. Conclusions Among patients with HTG-AP and elevated D-dimer, reduced AT-III was associated with a higher observed frequency of organ failure during hospitalization. These findings support further evaluation of AT-III as a routinely available coagulation marker in HTG-AP.