The aim of this study is to identify independent risk factors for 30-day mortality in patients aged 80 and over who have undergone major abdominal surgery. While traditional risk scoring systems often focus on chronic disease burden, they may not fully capture the biological decline associated with aging. This research specifically focuses on the predictive value of "frailty" and "physiological reserve" in determining surgical outcomes for this "old-old" patient population.

In this retrospective cohort study, data from approximately 200 patients treated between 2022 and 2025 will be analyzed. Frailty will be assessed using the Modified Frailty Index (mFI-5), and physiological reserve will be evaluated through preoperative laboratory markers such as albumin, creatinine, and lymphocyte counts. By determining how these factors influence postoperative mortality, the study aims to improve preoperative patient selection, enhance risk communication with families, and provide a basis for protective strategies like prehabilitation.

As the global population ages, the "old-old" (aged 80 and over) patient group is increasingly encountered in surgical clinics. Major abdominal surgery in this demographic is categorized as high-risk due to both the severity of surgical trauma and the presence of multiple comorbidities. Traditional risk assessment tools often emphasize chronic disease burden but may fail to reflect the loss of biological resilience inherent in aging. "Frailty" has emerged as a critical parameter in predicting surgical outcomes, representing a state of reduced physiological reserve and increased vulnerability to stressors, independent of chronological age.

This retrospective study is designed to investigate the independent predictors of 30-day mortality in patients aged 80 and older who underwent major abdominal surgery (including gynecologic oncology, surgical oncology, and urologic oncology procedures) at Dr. Abdurrahman Yurtaslan Ankara Oncology Training and Research Hospital.

Methodology and Data Collection:

Patient data from the years 2022, 2023, 2024, and 2025 will be extracted from the hospital's electronic database. The study will include approximately 200 patients who meet the inclusion criteria.

Frailty Assessment: The Modified Frailty Index (mFI-5) will be utilized to evaluate the frailty status of each patient. This index is a validated tool for retrospective studies and includes parameters such as functional status and history of specific comorbidities.

Physiological Reserve: This will be assessed using objective preoperative clinical and laboratory parameters, including serum albumin levels, creatinine, leukocyte/lymphocyte ratios, hemoglobin levels, and the American Society of Anesthesiologists (ASA) physical status score.

Outcome Measure: The primary endpoint is 30-day postoperative mortality. If 30-day follow-up data is not available in the hospital records, patients or their relatives will be contacted via telephone to determine the survival status.

Inclusion Criteria:

• Patients aged 80 years and older
• Underwent major abdominal surgery between January 2022 and December 2025
• Availability of at least 30 days of postoperative follow-up data
• Complete medical records available in the hospital information system

Exclusion Criteria:

• Patients under 80 years of age
• Underwent surgical procedures other than major abdominal surgery
• Missing or incomplete follow-up data within the first 30 days postoperatively
• Insufficient data for the assessment of frailty (mFI-5) or physiological reserve parameters (e.g., missing preoperative laboratory values)

The study population consists of "old-old" patients (aged 80 years and older) who underwent major abdominal surgery at a tertiary oncology center (Dr. Abdurrahman Yurtaslan Ankara Oncology Training and Research Hospital) between January 2022 and December 2025. This population includes patients who received surgical interventions in the departments of surgical oncology, gynecologic oncology, and urologic oncology. The sample represents a high-risk geriatric group undergoing complex oncological or major abdominal procedures, where frailty and physiological reserve are critical factors for survival.

To protect patient privacy and comply with institutional data protection policies