PWE-148 Combined effects of reoperation and venous thromboembolism in gastrointestinal surgery: evaluation of postoperative complications using linked hospital and primary care data

Introduction Trends towards early hospital discharge mean that complications such as venous thromboembolism (VTE) may increasingly occur in the primary care setting. Guidelines recommend thromboprophylaxis after hospital discharge in patients undergoing gastrointestinal cancer resection. However factors other than the presence of malignancy may prolong VTE risk. Previous studies have shown increased VTE risk with reoperation. The combined effect of VTE and reoperation on mortality has not been reported. Method Thirty-day reoperation, 90-day VTE and 90-day mortality was measured using linked Clinical Practice Research Datalink (CPRD), Hospital Episodes Statistics (HES), Office of National Statistics (ONS) and National Cancer Intelligence Network databases. The effect of different types of reoperation on VTE risk adjusted for length of hospital stay and other short-term complications was evaluated in adults undergoing one of seven gastrointestinal surgical procedures. The combined effect of VTE and reoperation on mortality was evaluated in benign and cancer patients separately. Results 76334 procedures over fifteen years were evaluated. Thirty-day reoperation was recorded in 3.18% (2426/76334) of procedures. There were 721/76334 (0.94%) VTE events recorded after 90 days of surgery (0.51% - 294/58036 in procedures for benign disease, 2.33% - 427/18298 in procedures for cancer). Over half (57.7%, 416/721) of VTE were recorded after hospital discharge. Reoperation was an independent predictor of 90-day VTE in benign (OR=1.88, p Conclusion Reoperation increased VTE risk in patients undergoing gastrointestinal surgery for benign conditions, while reoperation and VTE acted synergistically to increase mortality in patients undergoing surgery for cancer. Reoperation was therefore associated with significant harm from VTE extending into the out-patient setting, which may infer the need for additional thromboprophylaxis in some patients. Disclosure of interest None Declared.