Among joint replacement surgery patients, the incidence of acute kidney injury (AKI) might be much higher than previously recognized.

AKI developed in nearly 15% of patients having an elective joint replacement procedure at a large Australian hospital. That’s far higher than the less than 2% incidence rate reported by previous studies, and even the up to 9% rate when emergency patients are included. If confirmed, it would represent a large number of potentially at-risk patients, since these procedures are quite common.

“In the context that any episode of AKI is associated with increased mortality, longer hospitalization and an increase in the odds of both further episodes of AKI and the later development of chronic kidney disease, an AKI rate of nearly 15% is worrying,” wrote lead researcher Lara A. Kimmel, MD, of the Alfred Hospital in Melbourne, and her colleagues. It likewise indicates a golden opportunity to maximize pre-operative management to potentially reduce these risks, they asserted.

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For the study, the researchers examined the medical records of 425 patients who had elective hip- or knee-replacement surgery at Alfred Hospital between 2011 and June 2013. The investigators determined factors associated with AKI based on objective RIFLE criteria, such as measurements of glomerular filtration rate (GFR) and creatinine level.

AKI developed in 14.8% of patients, according to results published online ahead of print in Clinical Kidney Journal. Increasing BMI was the most significant factor. Obesity is an established risk factor for AKI, and the median BMI of this group was over 31 kg/m2. Older age and lower preoperative GFR were also associated with higher odds of the disease, in line with previous research.

Patients taking ACE inhibitors or angiotensin receptor blockers (ARBs) had more than twice the odds of AKI. Paradoxically, taking nonsteroidal anti-inflammatory drugs  after surgery appeared to be protective.

“Armed with the knowledge that the role of medications is important and likely mediated through a renal perfusive mechanism, a cautious approach to short-term peri-operative discontinuation and staged reintroduction on the basis of blood pressure and biochemistry seems appropriate…” the investigators suggested.

For most patients, AKI resolved by the time they were discharged from the hospital. However, an increased mortality risk persists even if renal function recovers, the researchers noted in the background information. They encouraged prospective research to further understand the short- and long-term risks of AKI in this patient population.


  1. Kimmel, LA, et al. Clin Kidney J, 2014; doi: 10.1093/ckj/sfu108