Curtis S. Bergquist, Elizabeth A. Jackson, Michael P. Thompson, Lourdes Cabrera, Gaetano Paone, Alphonse DeLucia, Chang He, Richard L. Prager, Donald S. Likosky, Michigan Society of Thoracic and Cardiovascular Surgeons Quality Collaborative

Prior work identified a direct relationship between frailty and adverse outcomes in cardiac surgery, but assessment of the effect across patient subgroups has largely been ignored. We identified whether frailty's (measured by gait speed) association with adverse outcomes differed across patient subgroups. We evaluated 53,932 patients undergoing cardiac surgery between 2011 and 2016 across 33 Michigan institutions. Five-meter gait speed (in seconds) was divided into groups: faster (<5.0), intermediate (5.0-5.99); slower (>=6.0). We used mixed logistic regression to estimate the relationship between increasing gait speed time and a patient's odds of major morbidity or mortality, adjusting for patient demographics, disease characteristics, surgeon and hospital. Effect modification by patient subgroup and gait speed test time was tested with interaction terms. Our secondary end point was an analysis of discharge disposition. Nearly one quarter (22.7%) of patients had at least one gait speed test. Slower (34% of patients) vs. faster (28%) patients were older (72.5yrs vs. 62.6yrs), had more comorbidities and developed our primary outcome (16.6% vs. 9.5%), p<0.0001. Significant interactions with gait speed existed for patient comorbidities (chronic lung disease, atrial fibrillation, p<0.05), though marginal interactions existed for patient age (p=0.059) and diabetes (p = 0.063). Slower patients were more often discharged to a facility rather than home. Slower gait speed was associated with increased odds of major morbidity or mortality. This effect was amplified among patients with pre-existing comorbidities. Future studies should evaluate the impact of pre-procedural interventions on frailty, including those aimed at addressing comorbidities.