Intraoperative Perfusion Index and Mortality

Composite Adverse Outcome

Proportion of participants who experience ≥1 of the following within 30 days after index surgery: 1. Postoperative admission to the intensive care unit 2. Reoperation (within 30 days) 3. Prolonged length of stay, defined as length of stay falling within the highest (75th-100th) percentile for the patient's surgical category 4. Acute kidney injury according to Kidney Disease: Improving Global Outcome (KDIGO) criteria (≥1.5-fold increase from baseline within 7 days after surgery or 0.3 mg dl-1 increase within 48 h)

Time frame: 30 days from time of surgery

Postoperative ICU Admission

Any ICU admission occurring after index surgery and within 30 days.

Time frame: 30 days from date of surgery

Reoperation

Any return to the operating room within 30 days of index surgery.

Time frame: 30 days from date of surgery

Prolonged Length of Stay (LOS)

Proportion of participants whose index-hospitalization LOS (days from surgery to discharge) falls in the 75th-100th percentile for their surgical category, determined from the study cohort distribution and assessed at discharge.

Time frame: Through hospital discharge (max. 6 months from surgery date)

Acute Kidney Injury

AKI defined by KDIGO criteria (≥1.5× baseline serum creatinine within 7 days or ≥0.3 mg/dL increase within 48 h) occurring within 30 days of surgery.

Time frame: 30 days from date of surgery