Predictors of Acute Kidney Injury After Hip Fracture in Older Adults

Introduction: This study aimed to investigate the prevalence of acute kidney injury (AKI) following hip fracture surgery in geriatric patients and to identify predictors for development of AKI with a focus on possible preventable risk factors.

Methods: In this retrospective cohort study, we reviewed electronic medical records of all patients above 65 years of age who underwent hip fracture surgery at Copenhagen University Hospital, Bispebjerg, Denmark, in 2018. Acute kidney injury was assessed according to the Kidney Disease Improving Global Outcomes guidelines. Multivariate logistic regression analyses were used to identify independent risk factors for AKI.

Results: Postoperative AKI developed in 28.4% of the included patients (85/299). Acute kidney injury was associated with increased length of admission (11.3 vs 8.7 days, P < .001) and 30-day mortality (18/85 vs 16/214, P = .001). In multivariable analysis, higher age (odds ratio [OR]: 1.05, 95% confidence interval [CI]: 1.01-1.08, P = .004), heart disease (OR: 1.78, 95% CI: 1.01-3.11, P = .045), and postoperative blood transfusion (OR: 1.84, 95% CI: 1.01-3.36, P = .048) were associated with AKI. Moreover, a higher postoperative C-reactive protein (199.0 ± 99.9 in patients with AKI, 161.3 ± 75.2 in patients without AKI) and lower postoperative diastolic blood pressure were observed in patients developing AKI.

Discussion and Conclusion: Acute kidney injury was common following hip fracture surgery and associated with longer admissions and increased mortality. Patients developing AKI were older and showed several postoperative similarities, including higher C-reactive protein, lower postoperative diastolic pressure, and the need for blood transfusion.