From age to physiological reserve: Frailty and muscle strength in early postoperative outcomes after abdominal surgery

Background: Chronological age is widely used to estimate surgical risk but may inadequately reflect early postoperative recovery. Markers of physiological reserve, including frailty and muscle strength, may better capture vulnerability to surgical stress. Methods: We conducted a prospective multicenter cohort study of 223 adults undergoing elective abdominal surgery. Frailty was assessed using a phenotype-based model, and handgrip strength (HGS) was measured at admission and discharge, with 90-day follow-up in a subset. Length of stay (LOS) and postoperative complications were analyzed using multivariable regression. Results: Frailty independently predicted prolonged LOS and postoperative morbidity, whereas age did not. Oncologic surgery showed the strongest association with extended hospitalization. Higher preoperative HGS was independently associated with shorter LOS. Acute perioperative changes in HGS were not associated with outcomes. Conclusions: Early postoperative recovery appears more closely related to physiological reserve than to age.