Preoperative frailty and adverse outcomes following coronary artery bypass grafting surgery in US veterans

Abstract

Background: Contemporary guidelines emphasize the value of incorporating frailty into clinical decision-making regarding revascularization strategies for coronary artery disease. Yet, there are limited data describing the association between frailty and longer-term mortality among coronary artery bypass grafting (CABG) patients.

Methods: We conducted a retrospective cohort study (2016-2020, 40 VA medical centers) of US veterans nationwide that underwent coronary artery bypass grafting (CABG). Frailty was quantified by the Veterans Administration Frailty Index (VA-FI), which applies the cumulative deficit method to render a proportion of 30 pertinent diagnosis codes. Patients were classified as non-frail (VA-FI ≤ 0.1), pre-frail (0.1 < VA-FI ≤ 0.2), or frail (VA-FI > 0.2). We used Cox proportional hazards models to ascertain the association of frailty with all-cause mortality. Our primary study outcome was 5-year all-cause mortality; the co-primary outcome was days alive and out of the hospital within the first postoperative year.

Results: There were 13,554 CABG patients (median 69 years, 79% White, 1.5% women). The mean pre-operative VA-FI was 0.21 (SD: 0.11); 31% were pre-frail (VA-FI: 0.17) and 47% were frail (VA-FI: 0.31). Frail patients were older and had higher co-morbidity burdens than pre-frail and non-frail patients. Compared with non-frail patients (13.0% [11.4, 14.7]), there was a significant association between frail and pre-frail patients and increased cumulative 5-year all-cause mortality (frail: 24.8% [23.3, 26.1]; HR: 1.75 [95% CI 1.54, 2.00]; pre-frail 16.8% [95% CI 15.3, 18.4]; HR 1.2 [1.08,1.34]). Compared with non-frail patients (mean 362[SD 12]), pre-frail (mean 361 [SD 14]; p < 0.01) and frail patients (mean 358[SD 18]; p < 0.01) spent fewer days alive and out of the hospital in the first postoperative year.

Conclusions: Pre-frailty and frailty were prevalent among US veterans undergoing CABG and associated with worse mid-term outcomes. Given the high prevalence of frailty with attendant adverse outcomes, there may be an opportunity to improve outcomes by identifying and mitigating frailty before surgery.

Keywords: coronary artery bypass grafting; coronary artery disease; frailty.