The relationship between chronic kidney disease (CKD) and acute kidney injury (AKI) is circular: surgical patients with preexisting CKD are at increased risk of AKI, and even mild or transient AKI is associated with future development of CKD.

In the November 1, 2017 JBJS, Gharaibeh et al. report findings from a retrospective cohort study with a nested case-control analysis that assessed the rate and risk factors associated with AKI after total hip arthroplasty (THA).

From a total of 10,323 THAs analyzed, AKI developed postoperatively in only 114 cases (1.1%). A multivariate analysis of the entire cohort identified four preoperative comorbidities that increased the risk of AKI by 2- to 4-fold: CKD, heart failure, diabetes, and hypertension. In addition to those risk factors, an analysis of the case-control cohort found that increasing BMI and perioperative blood transfusions were also associated with a higher risk of AKI.

Using data from the entire cohort, the authors developed an AKI risk calculator focused on presurgical variables (see graph). Based on that model, which will require independent validation, a 65-year-old man with either CKD or heart failure would have a 2% risk of AKI; the risk would increase to 4% if that patient had CKD and hypertension and to 16.1% in the presence of CKD, hypertension, and heart failure.

The anticipated increase in demand for joint replacements could lead to US surgeons performing approximately 572,000 THAs during the year 2030. A certain (and possibly increasing) proportion of those future procedures will occur in patients who have hypertension, diabetes, heart failure, and/or chronic kidney disease. The findings from Gharaibeh et al., especially the yet-to-be-validated AKI risk score, could help hip surgeons better counsel patients and identify those who might benefit from heightened postsurgical monitoring of kidney function.