Frailty as an independent risk factor for prolonged postoperative length of stay: A retrospective analysis of 2015-2019 ACS NSQIP data

Background: Frailty, a syndrome of decreased resilience to physiologic stress, has been associated with increased postoperative length of stay (LOS) for specific procedures. Yet, the literature lacks large-scale analyses examining the relationship between frailty and LOS across surgical procedure.

Study design: We conducted a retrospective cohort study of patients aged 65+ undergoing inpatient surgery including emergency procedures between 2015 and 2019 using American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP®) data. Frailty, measured by the modified 5-item frailty index (mFI-5), was categorized as non-frail (mFI-5 < 2) or frail (mFI-5 ≥ 2). We modeled LOS, adjusting for demographic variables, comorbidities, and surgical factors, and conducted a subgroup analysis based on emergency surgery status and surgical procedure type.

Main results: Among 1,254,809 patients, 29.0 % were frail. A higher proportion of frail patients were Black (10 % vs. 5.5 %), Hispanic (6.1 % vs. 3.8 %), of ASA class IV/V (23.3 % vs. 9.1 %), malnourished (2.7 % vs. 1.9 %), and underwent vascular surgery (16.5 % vs. 8.3 %). They experienced longer median LOS across all surgical procedures, except bariatric surgery. Unadjusted analysis revealed that mFI-5 scores of 4 and 5 were associated with increased median LOS by 3.5 days (95 % CI 3.36-3.64) and 4.64 days (95 % CI 3.96-5.32), respectively, compared to mFI-5 scores of 0. In adjusted analysis, frailty remained a significant risk factor for increased median LOS, with an mFI-5 score of 5 associated with a 3-day longer increase (95 % CI 2.79-3.22) compared to an mFI-5 score of 0. Subgroup analysis showed that each one-point increase in mFI-5 score had the strongest association with increased median LOS in emergency surgery (0.5 days, 95 % CI 0.48-0.52) and lower extremity bypass surgery (0.53 days, 95 % CI 0.47-0.59).

Conclusions: Frailty is an independent risk factor for prolonged postoperative LOS among older surgical patients, even after adjustment for patient and procedure covariates. Other independent risk factors for increased LOS include emergent surgery, malnutrition, and higher ASA class.