Acute Kidney Injury in Urology Patients: Incidence, Causes and Outcomes

Background: Acute kidney injury (AKI) is common in hospitalised patients and is associated with high mortality rates. However, the epidemiology of AKI in urology patients may differ due to a higher proportion of post-renal causes and surgical procedures that result in the intentional removal of renal parenchyma. Objectives: We performed a study to examine the incidence, aetiology and outcomes of AKI in a urological population. Patients and Methods: We performed a single-centre observational study including all hospitalised patients who sustained AKI within the Urology Department over an 18 month period. Patients with AKI were prospectively identified by a hospital-wide, electronic AKI reporting system that also allows demographic, hospital admission and co-morbidity data collection. Data regarding aetiology of AKI and details of surgical procedures were added retrospectively by manual case-note search. Results: 587 episodes of AKI occurred in 410 urology patients, giving an overall incidence of 6.7%. 137 (33.4%) were elective cases of whom 58 had undergone nephrectomy (radical and partial). Urinary obstruction and sepsis were the predominant causes of AKI in the 273 patients (66.6%) admitted as an emergency. Overall 30-day mortality was 7.8%; increasing severity of AKI was associated with mortality (4.8% in stage 1, 9.1% in stage 2, 14.9% in stage 3, P = 0.007). At time of discharge, only 57.7% of patients had recovered pre-morbid renal function. The observational nature of this study is a limitation, preventing determination of causality of associations. Conclusions: AKI is common in urology patients. The underlying aetiologies of AKI in this group may explain a lower overall mortality, although increasing AKI severity remains a marker of patients at higher risk of poor outcomes. The low rate of renal recovery suggests that urology patients who sustain AKI are exposed to a significant risk of CKD and its attendant consequences for long term health.