Published in:
01-04-2017 | Reports of Original Investigations
Assessing the accuracy of algorithm-derived cardiorespiratory fitness in surgical patients: a prospective cohort study
Published in: Canadian Journal of Anesthesia/Journal canadien d'anesthésie | Issue 4/2017
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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 CRFA and both CRF6MWD and CRFDASI was 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 CRFA and CRF6MWD were highly correlated (Pearson r = 0.878; P < 0.001). CRFA and CRFDASI were 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 CRFDASI were equivalent.
Conclusion
A non-exercise algorithm can estimate cardiorespiratory fitness in patients presenting for elective surgery. The variables required to compute CRFA can be obtained in a clinic setting without the need to engage in formal exercise testing. Further evaluation of CRFA as a predictor of long-term outcome in patients is warranted.