The Systemic Immuno-Inflammation Index (SII) is a ratio derived from complete blood count parameters (neutrophils, lymphocytes, platelets) and is a non-invasive and easily calculable biomarker. The SIPI effectively reflects both local and systemic inflammatory responses in the human body. It has been used to predict and evaluate the prognosis of various solid tumors such as gastric cancer, non-small cell lung cancer, and colorectal cancer. Furthermore, the SIPI has been shown to have significant prognostic value in cardiovascular and cerebrovascular diseases. In this study, the SIPI will be calculated using laboratory data at the time of admission to the intensive care unit, and the relationship between the obtained values and the 30-day mortality status of the patients will be analyzed.

Inclusion Criteria:

• The patient must be 65 years of age or older (in the geriatric age group),
• Admitted to the intensive care unit after elective or emergency surgery
• Have access to complete blood count (hemogram) data (neutrophils, lymphocytes, platelets) during their stay in the intensive care unit
• Be able to undergo 30-day mortality monitoring from the date of admission to the intensive care unit
• Have provided informed consent from the patient or their legal representative.

Exclusion Criteria:

• Patients under 65 years of age
• Patients admitted to the intensive care unit for non-surgical reasons (e.g., trauma, medical intensive care indications)
• Patients with deficient neutrophil, lymphocyte, or platelet counts upon admission to the intensive care unit
• Patients with a history of malignancy, hematological disease, or immunosuppressive therapy
• Terminally ill palliative patients
• Patients who refuse informed consent.

65 years of age or older postoperative patients