Effect of timing of perioperative chemical thromboprophylaxis on thromboembolic, bleeding, and other complications during and after antireflux surgery: multicentre cohort study

BACKGROUND: Although guidelines recommend the use of perioperative chemical thromboprophylaxis for antireflux surgery, the optimal timing for its initiation is unknown. The aim of this study was to investigate whether perioperative timing of chemical thromboprophylaxis affects bleeding, symptomatic venous thromboembolism, and complication rates in patients undergoing antireflux surgery. METHODS: This study involved analysis of prospectively maintained databases and medical records of all elective antireflux surgeries in 36 hospitals across Australia over 10 years. RESULTS: Overall, chemical thromboprophylaxis was given early (before surgery or intraoperatively) in 1099 (25.6 per cent) patients, and after surgery in 3202 (74.4 per cent) patients, with comparable exposure doses between the two groups. Symptomatic venous thromboembolism risk was unrelated to chemical thromboprophylaxis timing (0.5 versus 0.6 per cent for early and postoperative chemical thromboprophylaxis respectively (odds ratio (OR) 0.97, 95 per cent c.i. 0.41 to 2.47, P = 1.000). Postoperative bleeding developed in 34 (0.8 per cent) patients, and 781 intraoperative adverse events were identified in 544 (12.6 per cent) patients. Both intraoperative bleeding and complications were associated with significantly higher postoperative morbidity affecting multiple organ systems. Importantly, compared with postoperative chemical thromboprophylaxis, early administration increased the risk of postoperative bleeding ((1.5 versus 0.5 per cent for early and postoperative chemical thromboprophylaxis respectively (OR 2.94, 95 per cent c.i. 1.48 to 5.84, P = 0.002)) and intraoperative adverse events ((16.1 versus 11.5 per cent for early and postoperative chemical thromboprophylaxis respectively (OR 1.48, 95 per cent c.i. 1.22 to 1.80, P < 0.001)), as well as independently predicted their occurrences. CONCLUSION: Intraoperative adverse events and bleeding that occur during and after antireflux surgery are associated with significant morbidity. Compared with postoperative chemical thromboprophylaxis, early initiation of chemical thromboprophylaxis confers a significantly higher risk of intraoperative bleeding complications, without appreciable additional protection from symptomatic venous thromboembolism. Therefore, postoperative chemical thromboprophylaxis should be recommended for patients undergoing antireflux surgery.