Background: Antithrombin is a small plasma glycoprotein synthesized in the liver that belongs to the serpin family of serine protease inhibitors and inactivates several enzymes in the coagulation pathway. It plays a leading major factor on coagulation pathway, therefore administration of antithrombin is essential to treat serious clinical conditions such as disseminated intravascular coagulation (DIC). Despite the theoretical benefits of antithrombin supplementation, the optimal antithrombin activity for heparin efficacy and the benefits of antithrombin supplementation in various disease entities are not yet fully understood.
Methods: The strict administration guidelines on antithrombin III in cases of DIC by the National Health Insurance Service and the Ministry of Food and Drug Safety complied as follows: antithrombin levels below 20 mg/dL in adults; antithrombin activity below 70% of normal in adults; total administration period of antithrombin must be carefully limited to within maximum 3 days, and the total administration dose must be below 7,000 international unit (IU), (loading dose, 1,000 IU in 1 hour: maintenance dose, 500 IU every 6 hours for 3 days).
Results: We identified 76 eligible for analysis according to the above-mentioned criteria in our institution (male/female, 59/17). Forty-four were identified to the non-survivor group and 32 patients were recognized as the survivor group. The baseline parameters in the non-survivor and survivor groups were comparable with no significant differences in age (66.5±18.1 vs. 66.0±16.2 years, P=0.90), sex (32/12 vs. 27/5, P=0.35), hospital length of stay (31.1±34.5 vs. 31.2±26.1 days, P=0.99), sequential organ failure assessment (SOFA) (7.3±2.5 vs. 6.6±2.0, P=0.22), simplified acute physiology score II (SAPS II) (46.0±8.8 vs. 43.5±9.2, P=0.23), cause for DIC (P=0.95), and underlying disease (P=0.38). The levels of antithrombin III on the day just before the administration significantly lower in the non-survivor groups than in the survivor groups (50.1%±13.6% vs. 57.6%±12.5%, P=0.01). The hemoglobin level in the 2nd day and 7th day after antithrombin III administration was significantly different between the non-survivor and survivor groups (9.9±1.9 vs. 11.0±2.0 g/dL, P=0.01, and 9.4±1.8 vs. 10.5±1.6 g/dL, P=0.006). The antithrombin III levels on the day of administration [area under the curve (AUC) =0.672] demonstrated significantly better prediction of mortality than the A antithrombin III levels on 1st day (AUC =0.552), the 2nd day (AUC =0.624), and 7th day (AUC =0.593).
Conclusions: Our study suggests that the antithrombin administration may be effective tools for DIC treatment, and may be more positively considered, especially in the cases of DIC, which is a frequent complication of septic shock, sepsis, and other critical disease entities and which is associated with a high level of mortality. Furthermore, our study also suggests that the total doses and periods of antithrombin administration, which recommended by national guidelines, may be insufficient, therefore prolongation of period and increase of total dose of antithrombin supplement might be necessary.
Keywords: Antithrombins; anticoagulation; antithrombin III; coagulation; disseminated intravascular coagulation (DIC).