Prediction of Acute Kidney Injury After Cardiac Surgery With Cardiopulmonary Bypass (AKI-CPB)

February 2, 2026 updated by: Mehmet Akif Yilmaz, Ataturk University

The Role of Preoperative Inflammation Markers, Renal Function, and Perfusion Stress in Predicting Acute Kidney Injury After Cardiac Surgery Under Cardiopulmonary Bypass: A Retrospective Cohort Study

Acute kidney injury (AKI) is a common and serious complication following cardiac surgery performed under cardiopulmonary bypass and is associated with increased morbidity, mortality, and prolonged hospital stay. Despite advances in perioperative management, the ability to accurately predict postoperative AKI remains limited.

Recent evidence suggests that preoperative inflammatory markers derived from routine laboratory tests, as well as indicators of intraoperative perfusion stress, may play an important role in the development of AKI. However, data evaluating these factors together in patients undergoing cardiac surgery with cardiopulmonary bypass are limited.

This retrospective observational cohort study aims to investigate the association between preoperative renal function, inflammatory indices, and intraoperative perfusion-related parameters with the development of postoperative AKI. Acute kidney injury will be defined according to the KDIGO serum creatinine criteria within the first 72 hours after surgery. The findings of this study may help identify patients at increased risk for AKI and contribute to improved perioperative risk stratification in cardiac surgery.

Study Overview

Status

Completed

Conditions

Detailed Description

Acute kidney injury (AKI) is a frequent complication after cardiac surgery performed under cardiopulmonary bypass (CPB) and represents a major determinant of short- and long-term adverse outcomes. The pathophysiology of postoperative AKI is multifactorial and involves hemodilution, non-pulsatile flow, ischemia-reperfusion injury, systemic inflammatory response, and alterations in renal perfusion during CPB. Despite similar surgical and anesthetic management, not all patients develop AKI, suggesting that preoperative patient-related factors and intraoperative perfusion stress play a critical role.

In recent years, easily accessible inflammatory indices derived from routine hematological and biochemical parameters, such as the neutrophil-to-lymphocyte ratio, systemic immune-inflammation index, and C-reactive protein to albumin ratio, have been proposed as potential predictors of postoperative complications, including AKI. In addition, intraoperative parameters reflecting perfusion stress, such as cardiopulmonary bypass duration, arterial lactate levels, and acid-base disturbances, may further contribute to renal injury. However, studies evaluating these factors together in the setting of cardiac surgery with CPB are limited.

This single-center, retrospective observational cohort study will include adult patients who underwent cardiac surgery under cardiopulmonary bypass. Demographic data, comorbidities, preoperative laboratory parameters, echocardiographic findings, and intraoperative CPB-related variables will be collected retrospectively from institutional medical records. Acute kidney injury will be defined and staged according to the KDIGO serum creatinine criteria within 48-72 hours after surgery. Urine output criteria will not be evaluated due to limitations inherent to retrospective data collection.

The primary objective of the study is to identify independent predictors of postoperative AKI by assessing the combined effects of preoperative renal function, inflammatory markers, and intraoperative perfusion stress parameters. Secondary objectives include evaluation of AKI severity and in-hospital mortality. Multivariable logistic regression and receiver operating characteristic analyses will be used to determine the predictive value of selected parameters.

By improving understanding of the factors associated with postoperative AKI, this study aims to support better perioperative risk stratification and inform future prospective investigations in patients undergoing cardiac surgery with cardiopulmonary bypass.

Study Type

Observational

Enrollment (Actual)

455

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Adult patients undergoing cardiac surgery with cardiopulmonary bypass at a single tertiary care center.

Description

Inclusion Criteria:

  • Adults aged 18 years or older
  • Patients who underwent cardiac surgery under cardiopulmonary bypass
  • Coronary artery bypass grafting, valve surgery, or combined cardiac surgery
  • Elective or emergency procedures

Exclusion Criteria:

  • Preoperative end-stage renal disease requiring dialysis
  • Preoperative serum creatinine level greater than 4.0 mg/dL
  • Off-pump cardiac surgery
  • Missing preoperative or postoperative serum creatinine data

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Postoperative AKI
Patients who developed acute kidney injury within 72 hours after cardiac surgery under cardiopulmonary bypass, defined according to the KDIGO serum creatinine criteria.
No Postoperative AKI
Patients who did not develop acute kidney injury within 72 hours after cardiac surgery under cardiopulmonary bypass according to the KDIGO serum creatinine criteria.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Postoperative Acute Kidney Injury
Time Frame: Within 72 hours after cardiac surgery
Development of acute kidney injury within 72 hours after cardiac surgery performed under cardiopulmonary bypass. Acute kidney injury will be defined according to the KDIGO serum creatinine criteria, based on an increase in serum creatinine of ≥0.3 mg/dL within 48 hours or ≥1.5 times baseline within 7 days. Urine output criteria will not be evaluated due to the retrospective nature of the study.
Within 72 hours after cardiac surgery

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Severity of postoperative AKI (KDIGO stage)
Time Frame: Within 72 hours after cardiac surgery (postoperative days 0-3); assessed using the highest serum creatinine value measured every 12 hours (6 measurements)
AKI severity will be classified as KDIGO Stage 1-3 based on the change between preoperative creatinine (measured within 48 hours preoperatively) and the highest postoperative serum creatinine within the first 72 hours
Within 72 hours after cardiac surgery (postoperative days 0-3); assessed using the highest serum creatinine value measured every 12 hours (6 measurements)
In-Hospital Mortality
Time Frame: From the date of cardiac surgery through hospital discharge (index hospitalization), assessed at hospital discharge (up to 90 days)
All-cause mortality during the index hospitalization following cardiac surgery, determined from hospital records
From the date of cardiac surgery through hospital discharge (index hospitalization), assessed at hospital discharge (up to 90 days)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Ataturk University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 30, 2026

Primary Completion (Actual)

February 2, 2026

Study Completion (Actual)

February 2, 2026

Study Registration Dates

First Submitted

January 6, 2026

First Submitted That Met QC Criteria

January 14, 2026

First Posted (Actual)

January 15, 2026

Study Record Updates

Last Update Posted (Actual)

February 4, 2026

Last Update Submitted That Met QC Criteria

February 2, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • AKI-CPB-RETRO-2025
  • 2026/1 (Atatürk University Clinical Research Ethics Committee)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be shared due to the retrospective nature of the study and institutional data protection and patient confidentiality regulations. Only de-identified aggregate data will be reported in publications.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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