Renal Angina Index for Predicting Acute Kidney Injury in Adult ICU Patients

NCT07863505 | Not Yet Recruiting

• 1 other identifier: 2026-SAEK-0459
• Study Type: observational
• Target: 324
• Locations: 1 country
• Sites: 1

Brief Summary

Acute kidney injury (AKI) is a frequent complication of critical illness and is associated with increased morbidity and mortality. Early identification of patients at risk of progressing to moderate-to-severe AKI may facilitate closer monitoring and timely implementation of kidney-protective strategies. This prospective observational cohort study will evaluate the predictive performance of the Renal Angina Index (RAI) for the development of Kidney Disease: Improving Global Outcomes (KDIGO) stage 2 or stage 3 AKI in adult intensive care unit patients. Consecutive eligible patients admitted to the participating adult intensive care unit will be enrolled. The RAI will be calculated 24 hours after ICU admission using routinely available clinical characteristics and the change in serum creatinine between ICU admission and 24 hours. The primary outcome will be the development of KDIGO stage 2 or stage 3 AKI during the subsequent 48 hours. AKI staging will incorporate serum creatinine, urine-output, and renal replacement therapy criteria according to KDIGO definitions. The predictive performance of RAI will be evaluated using receiver operating characteristic analysis and the prespecified RAI threshold of ≥10. Secondary outcomes will include 7-day and 30-day intensive care unit mortality, intensive care unit length of stay, and duration of invasive mechanical ventilation.

Conditions

Acute Kidney Injury

Keywords

Renal Angina Index; Acute Kidney Injury; Intensive Care Unit; Critically Ill Adults; Kidney Injury Prediction; Risk Stratification

Outcome Measures

Primary Outcomes (1)

• Area Under the Receiver Operating Characteristic Curve of the Renal Angina Index for Predicting KDIGO Stage 2 or Stage 3 Acute Kidney Injury

  The predictive discrimination of the Renal Angina Index (RAI), calculated 24 hours after intensive care unit admission, for the development of Kidney Disease: Improving Global Outcomes (KDIGO) stage 2 or stage 3 acute kidney injury (AKI) during the subsequent 48 hours will be assessed using the area under the receiver operating characteristic curve (AUROC), with a 95% confidence interval. The target outcome will be development of KDIGO stage 2 or stage 3 AKI within 48 hours after RAI calculation. KDIGO stage 2 AKI will be defined as serum creatinine 2.0-2.9 times baseline or urine output \<0.5 mL/kg/hour for at least 12 hours. KDIGO stage 3 AKI will be defined as serum creatinine ≥3.0 times baseline, serum creatinine ≥4.0 mg/dL in the setting of AKI, initiation of acute renal replacement therapy, urine output \<0.3 mL/kg/hour for at least 24 hours, or anuria for at least 12 hours. When more than one criterion is met, the highest KDIGO stage reached will determine AKI severity.

  Within 48 hours after RAI calculation

Secondary Outcomes (5)

• Development of KDIGO Stage 2 or Stage 3 Acute Kidney Injury Within 48 Hours After RAI Calculation

  Within 48 hours after RAI calculation

• 7-Day Intensive Care Unit Mortality

  Within 7 days after ICU admission

• 30-Day Intensive Care Unit Mortality

  Within 30 days after ICU admission

• Intensive Care Unit-Free Days Through Day 30

  From ICU admission through day 30

• Ventilator-Free Days Through Day 30

  From ICU admission through day 30

Study Arms (1)

Eligible Adult ICU Patients

A single prospective cohort of consecutive eligible adult patients admitted to the participating intensive care unit. The Renal Angina Index (RAI) will be calculated 24 hours after ICU admission using routinely collected clinical and laboratory data. Participants will subsequently be analyzed according to the prespecified RAI strata of \<10 and ≥10. No treatment assignment will be made by the study protocol.

Diagnostic Test: Renal Angina Index Assessment

Interventions

Renal Angina Index Assessment DIAGNOSTIC_TEST

The Renal Angina Index will be calculated 24 hours after ICU admission using routinely available clinical and laboratory information. The RAI will be used as a prognostic index to evaluate the risk of subsequent KDIGO stage 2 or stage 3 acute kidney injury. No treatment, diagnostic procedure, or therapeutic intervention will be assigned on the basis of the RAI by the study protocol.

Eligible Adult ICU Patients

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Probability Sample

Study Population

Adult patients admitted to the participating adult intensive care unit will be considered for enrollment. Consecutive admissions meeting the eligibility criteria will be screened regardless of admission source or subsequently calculated Renal Angina Index category. The Renal Angina Index will be calculated 24 hours after ICU admission using routinely collected clinical and laboratory data.

You may qualify if:

• Age 18 years or older.
• Admission to the participating adult intensive care unit.
• Availability of serum creatinine measurements at ICU admission and 24 hours after ICU admission.
• Availability of a stable outpatient serum creatinine measurement obtained within the 6 months preceding ICU admission that can be used as the baseline value for KDIGO acute kidney injury staging.
• Availability of the clinical and laboratory data required to calculate the Renal Angina Index at 24 hours after ICU admission.
• Availability of serum creatinine and urine-output data required for assessment of the primary outcome during the 48 hours following Renal Angina Index calculation.
• Written informed consent from the participant or a legally authorized representative.

You may not qualify if:

• Age younger than 18 years.
• KDIGO stage 2 or stage 3 acute kidney injury present at ICU admission or developing before calculation of the Renal Angina Index at 24 hours after ICU admission.
• Initiation of acute renal replacement therapy before calculation of the Renal Angina Index.
• End-stage kidney disease requiring chronic renal replacement therapy.
• History of kidney transplantation.
• Absence of an eligible stable outpatient baseline serum creatinine measurement within the 6 months preceding ICU admission.
• Death, discharge, or transfer from the ICU within the first 24 hours after admission, preventing calculation of the Renal Angina Index.
• Insufficient data for assessment of the primary outcome during the 48-hour period following Renal Angina Index calculation.
• Pregnancy.

Sponsors & Collaborators

• Izmir Katip Celebi University: lead

Study Sites (1)

Izmir Katip Celebi University Ataturk Training and Research Hospital

Izmir, İzmir, 35360, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Acute Kidney Injury

Condition Hierarchy (Ancestors)

Renal Insufficiency; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Male Urogenital Diseases

Study Officials

• Senem Girgin, M.D.

  Izmir Katip Celebi University Atatürk Training and Research Hospital

  PRINCIPAL INVESTIGATOR

• Murat Aksun, M.D.

  Izmir Katip Celebi University Atatürk Training and Research Hospital

  STUDY DIRECTOR

Central Study Contacts

Dilara Dilan Fidan Menekşe, M.D.

CONTACT

+90 545 636 76 80; dln.fidan@hotmail.com

Ahmet Salih Tüzen, M.D.

CONTACT

+90 535 391 55 77; astuzen@icloud.com

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: October 2, 2026
• First Posted: October 7, 2026
• Study Start (Estimated): November 1, 2026
• Primary Completion (Estimated): November 1, 2027
• Study Completion (Estimated): November 30, 2027
• Last Updated: October 7, 2026

Record last verified: 2026-10

Locations

TU (1)