Risk factors for anastomotic leakage after rectal cancer surgery: a case‐control study

BACKGROUND: With introduction of the total mesorectal excision technique and preoperative radiotherapy in rectal cancer surgery, the local recurrence rate has decreased and the overall survival has improved. One drawback, however, is the high anastomotic leakage rate of approximately 10-18%. Male gender and low anastomoses are known risk factors for such leakage. The aim of this study was to identify potentially modifiable risk factors. METHOD: In a case-control study, data from the Swedish Rectal Cancer Registry (1995-2000) were analysed. Cases were all patients with anastomotic leakage after an anterior resection (n = 134). Two controls were randomly selected for each case. The medical records (n = 402) were checked against a study protocol. Due to incorrect recording two cases and 28 controls were excluded from further analyses. RESULTS: In the multivariate analysis significant risk factors were American Society of Anesthesiologists score > 2 OR = 1.40 (95% CI 1.05-1.83), preoperative radiotherapy OR = 1.34 (95% CI 1.06-1.69), intraoperative adverse events OR = 1.85 (95% CI 1.32-2.58), level of anastomosis <or= 6 cm OR = 1.39 (95% CI 1.01-1.90) and severe bleeding OR = 1.45 (95% CI 1.14-1.84). Diverting stoma protected from leakage OR = 0.68 (95% CI 0.52-0.88). Male gender was a risk factor in the univariate but not in the multivariate analysis OR = 1.30 (95% CI 1.04-1.63) and OR = 1.26 (95% CI 1.00-1.58), respectively. Except for a protective stoma, none of the variables considered as possible targets for improvement, such as postoperative epidural anaesthesia, observation at intensive care unit for more than 24 h, and intraabdominal drainage, proved to be protective factors either in the univariate or in the multivariate analyses. CONCLUSION: The most important risk factors for leakage were adverse intraoperative events, low anastomoses and preoperative radiotherapy. A diverting stoma is protective and can reduce the consequences when leakage occurs. Further analyses with focus on the surgical technique and individual surgeon may be valuable in identifying targets for improvement.