Risk Factors for Acute Kidney Injury After Hip Fracture Surgery in the Elderly Individuals

Abstract

Objective: We aimed to evaluate possible risk factors assocıated wıth acute kidney injury (AKI) after hip fracture surgery in the elderly individuals. Design: Level II diagnostic study, evidence obtained from prospective cohort study from 1 center with level 2, and 3 patients. Patients: A total of 165 patients (>65 years) with femoral neck fracture were enrolled in this prospective study between 2007 and 2010. Two patients were dropped for inadequate laboratory follow-up data. Patients with kidney failure or renal replacement therapy (RRT) history or AKI at admission were excluded. Intervention: Nephrology consultation was obtained from all patients at admission. All patients had undergone bipolar cemented hip arthroplasty that was performed by the same surgical team in all patients within 24 hours of fracture and admission under the same protocol. Main Outcome Measurements: Serum creatinine (SCr), urine output, and complete blood counts were evaluated at baseline and daily basis thereafter. The AKI was defined based on Acute Kidney Injury Network classification. Hospital charges were converted from Turkish Liras to US dollars and rounded. Results: Among 163 patients, AKI occurred in 25 (15.3%) patients, all within the first 48 postoperative hours. Three (1.8%) patients required RRT. Baseline SCr levels were restored within 4.84 ± 1.34 days on average (3-8 days). No patient required RRT after discharge. The mean hospital stay was 3 days (2-6 days) longer and the hospital charge was 2500 US$ higher for the patients with AKI. After multivariable adjustment, only lower estimated glomerular filtration rate levels (odds ratio 0.945, 95%confidence interval 0.92-0.96) emerged as an independent predictor for AKI. Conclusion: The AKI represents a frequent complication after hip fracture surgery associated with longer hospital stay and higher treatment costs with increased morbidity. Our results show baseline renal function is an independent predictor of AKI.