Cohort profile: PeRiOperative sTress risk assEssment and Clinical decision cohorT (PROTECT), a multi-center observational study based on real-world data

Background Global surgical volumes continue to rise, yet postoperative morbidity and mortality remain substantial, particularly among geriatric patients. The scarcity of multi-center prospective perioperative cohorts with active follow-up and large-scale, high-quality data limits the understanding of risk profiles and hinders individualized perioperative management in this population. To address this gap, the PeRiOperative sTress risk assEssment and Clinical decision cohorT (PROTECT) was established by creating a dedicated perioperative data platform for geriatric patients. This cohort profile specifically describes the study design, recruitment strategy, data structure, and current status of PROTECT. Methods PROTECT is an ongoing, ambispective, real-world observational cohort across three tertiary medical centers. The study continuously enrolls inpatients aged ≥ 65 years undergoing surgery under anesthesia. Preoperatively, standardized pre-anesthesia assessments are conducted to collect comprehensive medical information. Intraoperatively, anesthetic and surgical data, along with high-frequency biosignals are recorded. Postoperative outcomes are evaluated at 48 hours, 7 days, and 30 days. Descriptive analyses were performed to summarize baseline characteristics and postoperative outcomes. Results The first participant was enrolled in August 2019. As of May 2025, 61,289 participants aged 65—100 years have been included. The median age is 71 years, and 44.4% are female. 52.2% are classified as American Society of Anesthesiologists physical status III or higher. The most common surgeries are abdominal (42.8%) and orthopedic (19.9%). Since October 2023, postoperative follow-up response rates have reached 96.5% at 48 hours, 77.7% at 7 days, and 72.1% at 30 days. The 30-day all-cause mortality rate is 0.7%. The most frequent postoperative adverse outcomes are pulmonary infection (13.0%), nausea (11.9%), hepatic dysfunction (9.9%), and intensive care unit admission (8.6%). Leveraging the PROTECT dataset, several prediction models for major postoperative complications have already been developed and implemented in clinical practice. Conclusions PROTECT provides one of the largest and most comprehensive perioperative datasets for geriatric population. It enables detailed characterization of risk profiles, morbidity, and mortality in geriatric patients, supports identification of contributors to adverse outcomes, and offers a robust platform for developing perioperative risk assessment tools and multivariable models to support clinical decision-making. Future expansions will include extending follow-up to 90, 180, and 365 days and recruiting additional participating centers. Trial registration Registered at chictr.org.cn on 15/10/2025 (ChiCTR2500110517).