Prophylactic gentamicin and flucloxacillin is associated with increased rates of acute kidney injury in orthopaedic surgery

Introduction and Aims: Rising rates of Clostridium difficile infection (CDI), including fatal cases, prompted a number of measures to be implemented in 2008 in Scottish hospitals aimed at reducing CDI. These measures included restricting the use of broad spectrum antibiotics. Within the Tayside region of Scotland, the antibiotic policy was changed from cefuroxime to flucloxacillin and gentamicin as prophylaxis in patients undergoing orthopaedic surgery. A recent small observational study carried out in Dumfries and Galloway has raised concerns that this change has led to increased rates of AKI. The aim of this study was to examine the rates of AKI before and after the antibiotic policy change in patients undergoing orthopaedic surgery.

Methods: Patients undergoing orthopaedic implant surgery between the 1st October 2006 and 30th September 2010 were studied. Data linkage was performed using anonymised record linkage via the Health Informatics Centre (HIC). Post-operative AKI was defined by AKIN criteria. Interrupted time series with segmented regression analysis of intervention effect was carried out in the two years before and after the change in antibiotic policy in October 2008.

Results: During the study period, 7698 patients were included in the analysis with 767 cases of AKI. Based on 200 operations performed every month, stage 1 AKIN increased from 4.3% to 7.6%, stage 2 increased from 0.4% to 1.1% and stage 3 increased from 0.2% to 1% following the policy change. Analyses using interrupted time series showed that there was a significant increase in slope after introduction of the policy (p=0.035), adjusted for gender, age and use of nephrotoxic drugs. In addition there was a significant change in all levels of severity of AKI after the policy change (Chi squared = 57.584 (p<0.001). 15 patients had persisting stage 2 and 15 patients had persisting stage 3 AKIN 7 days post-operatively. There was no change in AKI among patients with fractured neck of femur group who received co-amoxiclav as prophylaxis throughout the study period.

Conclusions: The change in antibiotic policy from cefuroxime to flucloxacillin and gentamicin was associated with increased rates of AKI in patients undergoing orthopaedic implant surgery within Tayside. This has led to a change in policy with co-amoxiclav now being given as prophylaxis to all patients undergoing orthopaedic surgery.