Background: Hip fracture is common in elderly patients and is associated with high morbidity and mortality. Acute kidney injury (AKI) following hip fracture may have additional impact on clinical outcomes.

Objectives: To investigate the incidence of AKI, the risk factors for its occurrence and impact on mortality, timing of surgery, and length of hospitalization (LOS) in patients undergoing hip fracture surgery.

Methods: We retrospectively examined the records of patients who underwent hip fracture surgery between 2013 and 2017. All patients had a baseline serum creatinine value and at least one later value. AKI was defined according to KDIGO guidelines.

Results: The study included 511 patients. Mean age was 72.6 years, 325 males (63.4%); 151 (29.5%) had baseline eGFR < 60 ml/min/1.73m². Of these, 87 (17%) developed AKI. Older age, diabetes mellitus, hypertension, and chronic heart condition were significantly more common in patients who developed AKI. Patients with AKI had increased 30-day mortality (hazard ratio [HR] 3.96, 95% confidence interval [95%CI] 1.62–9.7, P = 0.003) and mortality at one year (HR 2.72, 95%CI 1.5–4.9, P = 0.002). AKI was associated with surgery delay > 48 hours (HR 2.241, 95%CI 1.206–4.165, P = 0.011). Mean LOS was 10.9 days and 8 days for patients with AKI and without, respectively, P < 0.0001.

Conclusions: AKI is a common complication in patients with hip fracture and is associated with increased short- and long-term mortality, delayed surgery, and longer hospitalization. Interventions identifying and monitoring patients at risk may contribute to improve the outcomes