Sepsis is a life-threatening condition characterized by organ dysfunction resulting from a dysregulated host response to infection and remains a leading cause of morbidity and mortality in intensive care units. Early identification of patients at high risk for adverse outcomes is essential for timely intervention and improved prognosis.

This prospective, single-center, non-interventional study aims to evaluate the predictive value of the combined use of the blood uric acid/albumin ratio (UAR) and serum lactate levels in patients aged 65 years and older who are admitted to the intensive care unit with a diagnosis of sepsis according to SEPSIS-3 criteria. Patients without acute kidney injury at admission and with at least 24 hours of intensive care follow-up will be included.

The primary outcome is the development of acute kidney injury within the first 7 days of ICU admission according to KDIGO criteria. Secondary outcomes include vasopressor requirement during ICU stay, changes in serum lactate levels over the first 24 hours, and 28-day mortality. The study seeks to determine whether the combination of UAR and lactate levels can serve as an easily accessible and clinically applicable biomarker to predict adverse outcomes and support prognostic assessment and treatment strategies in sepsis patients.

Inclusion Criteria:

• Patients aged 65 years and older
• Diagnosis of sepsis according to SEPSIS-3 criteria
• Admission to the intensive care unit
• No acute kidney injury at admission according to KDIGO classification
• Measurement of serum uric acid, albumin, and lactate levels at ICU admission
• SOFA score calculated at ICU admission
• ICU follow-up of at least 24 hours

Exclusion Criteria:

• Age under 65 years
• Uncompensated or decompensated chronic liver disease (e.g., Child-Pugh class C)
• Chronic kidney disease stage 4 or 5 (eGFR <30 mL/min/1.73 m²)
• Presence of acute kidney injury at admission according to KDIGO criteria
• Active malignancy or receipt of active cancer treatment within the last 6 months
• Missing or incomplete clinical/laboratory data
• ICU follow-up less than 24 hours

The study population consists of critically ill adult patients aged 65 years and older who are admitted to a tertiary-level intensive care unit with a diagnosis of sepsis based on SEPSIS-3 criteria. All participants are required to have baseline measurements of serum uric acid, albumin, and lactate levels at the time of ICU admission and no evidence of acute kidney injury at presentation. The study focuses on evaluating the prognostic value of routinely available biochemical markers in predicting adverse clinical outcomes, including acute kidney injury, vasopressor requirement, and short-term mortality during intensive care follow-up.