Risk of Acute Kidney Injury with gentamicin as surgical prophylaxis

In 2008 Scottish Government issued a new target to reduce Clostridium difficile infection by 30% in three years. Consequently Scottish hospitals restricted antibiotics with high risk for Clostridium difficile and changed from cephalosporins to gentamicin for surgical antibiotic prophylaxis. In response to physicians’ concerns regarding increasing rates of postoperative acute kidney injury (AKI), this study aimed to examine postoperative AKI before and after the use of gentamicin in surgical prophylaxis. The study population was all adults undergoing surgery with antibiotic prophylaxis (orthopaedics, urology, vascular, gastrointestinal and gynaecology) between the 1st October 2006 and 30th September 2010. Post-operative AKI was defined by the Kidney Disease Improving Global Outcomes criteria. Study design was an interrupted time series with segmented regression analysis. 12,482 patients were included in the study. In orthopaedic patients, change in policy was associated with a 94% increase in AKI (p=0.04, 95% CI 93.894.3%). The antibiotic policy change was not associated with significant increase in AKI in any of the other groups. Rates of postoperative AKI in vascular surgery were high at 24%, increased in gastrointestinal surgery steadily throughout the study period and could only be ascertained in 52% urology and 47% gynaecology patients due to lack of creatinine testing. The change in antibiotic policy from cefuroxime to flucloxacillin (2 doses of 1g) and single dose gentamicin (4mg/kg) was associated with increased rates of AKI in patients undergoing orthopaedic surgery within the Tayside region of Scotland and so should be avoided in orthopaedic patients in the peri-operative period. Our findings also raise concerns about the increasing prevalence of postoperative AKI and of failures to consistently measure postoperative renal function.