Costs and outcomes of acute kidney injury (AKI) following cardiac surgery

Abstract

Background. Acute kidney injury (AKI) is a recognized complication of cardiac surgery; however, the variability in costs and outcomes reported are due, in part, to different criteria for diagnosing and classifying AKI. We determined costs, resource use and mortality rate of patients. We used the serum creatinine component of the RIFLE system to classify AKI. Methods. A retrospective cohort study was conducted from the electronic data repository at the University of Pittsburgh Medical Center of patients who underwent cardiac surgery and had an elevation (≥0.5 mg/dl) of serum creatinine postoperatively. Data were compared to age-and APACHE IIImatched controls. Cost, mortality and resource use of AKI patients were determined postoperatively for each of the three RIFLE classes on the basis of changes in serum creatinine. Results. Of the 3741 admissions, 258 (6.9%) had AKI and were classified as RIFLE-R 138 (3.7%), RIFLE-I 70 (1.9%) and RIFLE-F 50 (1.3%). Total and departmental level costs, length of stay (LOS) and requirement for renal replacement therapy (RRT) were higher in AKI patients compared to controls. Statistically significant differences in all costs, mortality rate and requirement for RRT were seen in the patients stratified into RIFLE-R, RIFLE-I and RIFLE-F. Even patients with the smallest change in serum creatinine, namely RIFLE-R, had a 2.2-fold greater mortality, a 1.6-fold increase in ICU LOS and 1.6-fold increase in total postoperative costs compared to controls. Discussion. Costs, LOS and mortality are higher in postoperative cardiac surgery patients who develop AKI using RIFLE criteria, and these values increase as AKI severity worsens.

Design of Clinical Trials in Acute Kidney Injury

“…For example, patients admitted to the hospital with community-acquired pneumonia have a 90-day mortality rate of 5% that increases to 10% in the setting of AKI (37). Similarly, hospital mortality after routine cardiothoracic surgery is generally low, at less than 2%, but increases to 11% in the setting of AKI (38). When studies in patients with AKI are being planned, it is critical to accurately assess the natural history of the diseases in the population with AKI and to integrate this knowledge with potential side effects of the drug or intervention to be studied.…”

ABT‐719 for the Prevention of Acute Kidney Injury in Patients Undergoing High‐Risk Cardiac Surgery: A Randomized Phase 2b Clinical Trial

“…Cardiac‐surgery–associated acute kidney injury (AKI) results in high resource utilization, in‐hospital mortality, permanent loss of renal function, and poor long‐term survival 1, 2, 3, 4. Patients undergoing cardiac surgery procedures performed with cardiopulmonary bypass (CPB; on‐pump) have a high risk of developing AKI 5…”

Biomarkers Predict Progression of Acute Kidney Injury after Cardiac Surgery

“…3,4 These definitions have aided in ascertainment of the true incidence of AKI after cardiac surgery and shown that AKI, regardless of severity or stage, is associated with longer length of intensive care unit (ICU) and hospital stay, increased cost of hospitalization, and increased patient mortality. 5,6 In recent years, several studies have shown that novel biomarkers can detect acute tubular injury earlier than serum creatinine in the setting of AKI. [7][8][9][10][11] Despite attempts to select patients at high risk for severe AKI, the majority of patients in these prospective studies do not develop clinical AKI.…”