Impact of Perioperative Acute Kidney Injury as a Severity Index for Thirty-Day Readmission After Cardiac Surgery

Abstract

Background Of patients undergoing cardiac surgery in the United States, 15–20% are re-hospitalized within 30-days. Current models to predict readmission have not evaluated the association between severity of post-operative acute kidney injury (AKI) and 30-day readmissions. Methods We collected data from 2,209 consecutive patients who underwent either coronary artery bypass (CABG) or valve surgery at seven member hospitals of the Northern New England Cardiovascular Disease Study Group Cardiac Surgery Registry (NNE) between July 2008 and December 2010. Administrative data at each hospital was searched to identify all patients readmitted to the index hospital within 30 days of discharge. We defined AKI Stages by the AKI Network definition of 0.3 or 50% increase (Stage 1), 2-fold increase (stage 2) and a 3-fold or 0.5 increase if the baseline serum creatinine was at least 4.0 (mg/dL) or new dialysis (stage 3). We evaluate the association between stages of AKI and 30-day readmission using multivariate logistic regression. Results There were 260 patients readmitted within 30-days (12.1%). The median time to readmission was 9 (IQR 4–16) days. Patients not developing AKI following cardiac surgery had a 30-day readmission rate of 9.3% compared to patients developing AKI stage 1 (16.1%), AKI stage 2 (21.8%) and AKI stage 3 (28.6%, p <0.001). Adjusted odds ratios for AKI stage 1 (1.81; 1.35, 2.44), stage 2 (2.39; 1.38, 4.14) and stage 3 (3.47; 1.85–6.50). Models to predict readmission were significantly improved with the addition of AKI stage (c-statistic 0.65, p = 0.001) and net reclassification rate of 14.6% (95%CI: 5.05% to 24.14%, p = .003). Conclusions In addition to more traditional patient characteristics, the severity of post-operative AKI should be used when assessing a patient’s risk for readmission.

TIMP-2*IGFBP7 (Nephrocheck®) Measurements at Intensive Care Unit Admission After Cardiac Surgery are Predictive for Acute Kidney Injury Within 48 Hours

“…This definition appears to be very strict, but recent literature indicates that AKI even in stage I carries a high impact on short- and long-term prognosis of patients. Patients experiencing AKI have a higher risk of mortality, readmission rates and a higher risk for developing heart failure as compared to patients without AKI [4, 5, 22, 23, 26, 27]. Using SCr or drop in urine volume to diagnose AKI is problematic, because both markers develop after tubular damage has occurred [7].…”

“…Measurement of [TIMP-2*IGFBP7] before surgery was not helpful to predict AKI, neither alone nor in combination with [TIMP-2*IGFBP7] values at ICU admission. AKI is a common complication after cardiac surgery with an incidence between 20-50% in patients undergoing cardiac surgery [2, 3, 22-25]. Stage I of AKI according to most recent guidelines is defined as a rise in SCr of ≥0.3mg/dl within 48 hours.…”

The Association of Acute Kidney Injury in the Critically Ill and Postdischarge Outcomes

“…AKI in patients with heart failure or following cardiac surgery is shown to be associated with readmission (20,21). With heightening societal and political interest in cost-effective healthcare delivery, AKI at the time of critical care may be a marker for critical illness survivors who are at high risk for subsequent adverse events.…”

Entanglement of Sepsis, Chronic Kidney Disease, and Other Comorbidities in Patients Who Develop Acute Kidney Injury

“…Postoperative AKI is associated with an increased risk of readmission, incidence, and progression of CKD, as well as poor long-term survival. 121,[125][126][127][128] Coca et al 126 recently showed that urinary biomarkers of tubular injury measured in the early postoperative period are NOTE. The Cleveland Clinic Score 96 was designed to predict RRT after adult surgery: a score of 0 carried an incidence of RRT of 0.13%, a score of 4 had an incidence of RRT of 2.3%, a score of 6 had an incidence of RRT of 8.0%, and a score of 10 had an incidence of RRT of 19.6%.…”