Frailty is a key predictor of adverse outcomes in older surgical patients, yet its longitudinal evolution and potentially reversible nature remain underexplored in perioperative settings. This study aimed to characterize postoperative frailty trajectories in older patients and to examine their association with one-year mortality, as well as factors influencing trajectory group.

Inclusion Criteria:

• Aged ≥65 years;
• Underwent elective non-cardiac, non-neurosurgical procedures;
• Completed standardized frailty assessments both preoperatively and postoperatively.

Exclusion Criteria:

• Severe dementia, language disorders, significant hearing or visual impairments, or coma;
• Cognitive function below the Mini-Mental State Examination (MMSE) thresholds (<18 for illiterate individuals, <21 for individuals with primary education, and <25 for individuals with secondary education or higher);
• Surgery performed under local anesthesia or monitored anesthesia care;
• Surgical duration ≤30 minutes;
• Missing data on postoperative complications or one-year mortality required for this study;
• Incomplete frailty assessments at 1, 3, and 6 months after surgery.

Patients' frailty was assessed using the FRAIL scale at four time points: preoperatively and at 1, 3, and 6 months postoperatively. Patients were classified into distinct frailty trajectory groups using latent class trajectory modeling. One-year all-cause mortality was ascertained through structured telephone follow-up.