Patients undergoing antithrombotic therapy (AT) have high risks of bleeding and thrombosis from their comorbidity.(22, 23) As those risks tend to be high when surgical intervention is required, several perioperative period protocols have been developed to prevent complications based on AT.(5–7) In contrast, the analysis of more than 400,000 surgical cases demonstrated that emergency procedures increase the risk of major postoperative morbidity and mortality.(24) Hence, the perioperative bleeding risk for patients undergoing AT may be expected to increase, making perioperative outcomes in an emergency setting a potential concern. Generally, as older people also have more comorbidities than young people, we hypothesize that perioperative complications will occur in patients with AT than those without AT.
Similar to other studies’ findings (8, 10), the patients in this study undergoing AT were older, have higher Charlson comorbidity index, and poor ASA・PS than those who were not undergoing AT (Table 2). Advanced age is a well-known risk factor of cardiovascular disease, such as stroke (25) and coronary artery disease (26).
In using pre-matching data, there were no differences in operation time and estimated blood loss, whereas there were more Clavien-Dindo classifications of grade II or greater, longer postoperative hospital stay, and higher hospital death rate in the AT group than in the Non-AT group (Tables 2 and 3). A higher Carlson-comorbidity index and postoperative diagnosis are negative predictors of mortality, postoperative complications, and postoperative stay in older patients.(27)
After adjusting these biases using the propensity score matching method, the estimated blood loss, perioperative blood transfusion, overall morbidity, and postoperative hospital stay were similar between the patients in both groups. Matsuoka et al. also demonstrated that antithrombotic drugs do not affect short surgical outcomes in their propensity score matching setting.(28) Additionally, Imamura et al. reported that there were no significant differences in blood loss, severe blood loss more than 100 ml, blood transfusion, and postoperative mortality for patients with or without antithrombotic therapy in emergency laparoscopic cholecystectomy.(17) These studies’ findings are line with our results, which may help surgeons in deciding the strategy for critical cases with antithrombotic therapy. Therefore, antithrombotic therapy does not affect perioperative short surgical outcomes in the situation of adjusting backgrounds.
We then evaluated the risk factors for the intraoperative severe bleeding needing blood transfusions in the all cohort. Because previous studies evaluating the correlation between blood loss and blood transfusion obtained cut-off values for severe bleeding using ROC curve analysis,(29) the cut-off value in this study was determined similarly, the optimal one and AUCs were 113 ml and 0.90, respectively. Although 113 ml is less than 750 ml (28) or 1000 ml (30) in previous studies, our results may be sustained with the use of new surgical instrumentations and techniques. Energy devices, including vessel-sealing devices and ultrasonically activated devices, have improved surgical outcomes in low anterior resection, liver transection, and hysterectomy. (31–33) These surgical techniques may be more effective in controlling intra- and postoperative bleeding in emergency surgery in patients undergoing antithrombotic therapy. Concerning the need for blood transfusion in cases of severe intraoperative bleeding, antithrombotic and antiplatelet drug use were not related. However, anticoagulant drug use was more controversial in here (Table 5). In the elective setting, two randomized clinical studies recently demonstrated that bleeding and thrombotic events after elective non-cardiac surgery had no significant differences between patients with or without interruption of antiplatelet agents.(34, 35) Concerning abdominal surgery, several studies demonstrated the safety and feasibility of discontinued single aspirin or clopidogrel use in gastrointestinal surgery and colorectal resection.(30, 36, 37) These results including ours suggested that discontinuing single antiplatelet drugs does not increase perioperative bleeding even in emergency surgery. Meanwhile, our results revealed that anticoagulant drug use is one of the risk factors for severe intraoperative bleeding. The previous study reported that bleeding and mortality for emergency surgery were significantly higher than those for elective surgery in general surgical patients receiving warfarin.(38) Therefore, surgeons should pay more attention to manage the risk of intraoperative blood loss and reduce the need for blood transfusion in emergency gastrointestinal surgery in patients taking anticoagulant drugs than those taking antiplatelet drugs.
Finally, we assessed the relationship between AT and postoperative bleeding. Here, there was a higher tendency of postoperative bleeding between patients taking and not taking dual antithrombotic drugs. The overall incidence of postoperative bleeding was low, and there were no statistical differences between the groups. The previous study reported that dual antiplatelet drugs increased postoperative bleeding.(30, 39) Therefore, as multiple antithrombotic drug use may increase postoperative bleeding complications in an emergency setting, careful postoperative management is necessary.
This retrospective study has several limitations. Several types of diseases were included, and the selection of surgical approach was not randomized. Antithrombotic therapy included many types and different generations of antiplatelet and anticoagulant agents. The total number of patients who underwent abdominal emergency surgery was relatively small in propensity score matching analyses. A comparison of the relationship between the patients with or without anticoagulant therapy in propensity score matched analysis was not performed due to their small number. Although administration of more than two anticoagulant drugs was a negative predictor for bleeding complications (30, 39), the present study included only two patients.