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The cardiopulmonary exercise test grey zone; optimising risk stratification by application of critical difference

Rose, G. A., Davies, R. G., Davison, Gareth W, Adams, R. A., Williams, I. A., Lewis, M. H., Appadurai, I. R. and Bailey, D. M. (2018) The cardiopulmonary exercise test grey zone; optimising risk stratification by application of critical difference. British Journal of Anaesthesia, 1 . pp. 1-8. [Journal article]

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DOI: 10.1016/j.bja.2018.02.062


Background: Cardiorespiratory fitness can inform patient care, although to what extent natural variation in CRF influencesclinical practice remains to be established. We calculated natural variation for cardiopulmonary exercise test(CPET) metrics, which may have implications for fitness stratification.Methods: In a two-armed experiment, critical difference comprising analytical imprecision and biological variation wascalculated for cardiorespiratory fitness and thus defined the magnitude of change required to claim a clinically meaningfulchange. This metric was retrospectively applied to 213 patients scheduled for colorectal surgery. These patientsunderwent CPET and the potential for misclassification of fitness was calculated. We created a model with boundariesinclusive of natural variation [critical difference applied to oxygen uptake at anaerobic threshold (V_O2-AT): 11 mlO2 kg�1 min�1, peak oxygen uptake (V_O2 peak): 16 ml O2 kg�1 min�1, and ventilatory equivalent for carbon dioxide at AT(VE/VCO2-AT): 36].Results: The critical difference for V_O2-AT, V_O2 peak, and V_ E/V_CO2-AT was 19%, 13%, and 10%, respectively, resulting infalse negative and false positive rates of up to 28% and 32% for unfit patients. Our model identified boundaries for unfitand fit patients: AT <9.2 and �13.6 ml O2 kg�1 min�1, V_O2 peak <14.2 and �18.3 ml kg�1 min�1, V_ E/V_CO2-AT �40.1 and<32.7, between which an area of indeterminate-fitness was established. With natural variation considered, up to 60% ofpatients presented with indeterminate-fitness.Conclusions: These findings support a reappraisal of current clinical interpretation of cardiorespiratory fitness highlightingthe potential for incorrect fitness stratification when natural variation is not accounted for.

Item Type:Journal article
Keywords:anaerobic threshold; cardiopulmonary exercise test; risk assessment
Faculties and Schools:Faculty of Life and Health Sciences > School of Sport
Faculty of Life and Health Sciences
Research Institutes and Groups:Sport and Exercise Sciences Research Institute
Sport and Exercise Sciences Research Institute > Centre for Physical Activity and Health
ID Code:40001
Deposited By: Mrs Julie Haydock
Deposited On:23 Apr 2018 08:21
Last Modified:23 Apr 2018 08:21

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