Assessing the accuracy of algorithm-derived cardiorespiratory fitness in surgical patients: a prospective cohort study

Abstract

© 2017, Canadian Anesthesiologists' Society. Purpose: To determine if a non-exercise algorithm-derived assessment of cardiorespiratory fitness (CRFA) accurately predicted estimated values obtained using a six-minute walk test (CRF6MWD) and the Duke Activity Status Index (CRFDASI). Methods: Following research ethics board approval, an observational cohort study was conducted in selected, consenting patients undergoing elective surgery. Participants completed questionnaires assessing their self-reported exercise capacity. Their height, weight, waist circumference, and vital signs were measured. A six-minute walk test was performed twice with a 45-min rest interval between tests. The correlation between CRFAand both CRF6MWDand CRFDASIwas determined. Results: Two hundred forty-two participants were included. Mean age was 62 (range 45-88 yr); 150 (62%) were male, 87 (36%) self-reported walking or jogging > 16 km per week, and 49 (20%) were current smokers. The CRFAand CRF6MWDwere highly correlated (Pearson r = 0.878; P < 0.001). CRFAand CRFDASIwere less strongly correlated (Pearson r = 0.252; P < 0.001). Among patients capable of walking > 427 m in the six-minute walk test, CRFA, CRF6MWD, and CRFDASIwere equivalent. Conclusion: A non-exercise algorithm can estimate cardiorespiratory fitness in patients presenting for elective surgery. The variables required to compute CRFAcan be obtained in a clinic setting without the need to engage in formal exercise testing. Further evaluation of CRFAas a predictor of long-term outcome in patients is warranted.