Associations between Frailty and Survival after Coronary Artery Bypass Graft Surgery: Propensity Score Analysis of 13,783 patients in ACS-NSQIP

S. Mu¹, S. Baek², H. Shakir^3
1Rutgers New Jersey Medical School, Newark, New Jersey ²Robert Wood Johnson Medical School, New Brunswick, New Jersey ³Rutgers University`, East Brunswick, New Jersey

Purpose: Frailty is a state of physiologic vulnerability to stress and many studies have demonstrated that increasing frailty is associated with worse postoperative outcomes. We wanted to evaluate the independent effect of frailty on postoperative mortality after CABG, using the novel 5 factor modified frailty index.

Methods: We used data from the 2016 to 2021 American College of Surgeons National Surgical Quality Improvement Program Participant User File (ACS NSQIP PUF) to compare survival outcomes after coronary artery bypass graft surgery by preoperative frailty. This cross-sectional clinical database of approximately 700 hospitals in the United States contains preoperative characteristics and outcomes including 30 day all-cause mortality. Preoperative congestive heart failure, diabetes, chronic obstructive pulmonary disease, hypertension, and dependent functional status each contribute 1 point to the 5-factor modified frailty index. We compared unadjusted survival between mFI5 groups using Kaplan-Meier estimates. Additionally, we used a multinomial propensity score weighted Cox proportional hazards model to compare the risk of death between patients of increasing frailty, adjusting for preoperative age, race, ethnicity, sex, smoking status, and preoperative dialysis use, renal failure, and bleeding disorders.

Results: 13,783 patients underwent CABG surgery from 2016 to 2021. The most common modified frailty score was 1 (n=5,667), followed by 2 (n=5,000), 0 (n=1,979), and 3+ (n=1,137). Those with mFI5 of 3+ were more likely to be older, female, have renal failure, and have longer operative duration.
326 (2.36%) of patients experienced death within 30 postoperative days. In the unadjusted analysis, increasing values of mFI-5 frailty were significantly associated with worse survival (p = 0.012). After propensity score weighting, compared to patients without frailty, patients with mFI5 score of 3 or more had a significantly increased hazard of death (HR 3.29, 95% CI: 2.04 to 5.29), but patients with scores of 1 and 2 were not at increased hazards of death (HR 0.93, 95% CI 0.62 to 1.41; HR 1.31, 95% CI 0.87 to 1.97, respectively).

Conclusion: Low or moderate levels of frailty, corresponding to modified 5 item frailty of 1 or 2, were not associated with increased mortality after CABG, but a high level of frailty (mFI-5>=3) was associated with markedly increased mortality. Routine frailty assessment in patients considered for CABG could improve risk stratification and identify patients who would benefit from interventions to mitigate the effects of this potentially modifiable risk factor.

Identify the source of the funding for this research project: None