Validation of preoperative cardiopulmonary exercise testing‐derived variables to predict in‐hospital morbidity after major colorectal surgery

West, M. A.; Asher, R.; Browning, M.; Minto, G.; Swart, M.;
Richardson, K.; McGarrity, L.; Jack, S.; Grocott, M. P. W.; Challand,
C.; wan Lai, C.; Struthers, R.; Sneyd, R.; Psarelli, E..

British Journal of Surgery: BJS, May 2016, Vol. 103 Issue: Number 6 p744-752,

Abstract: In single‐centre studies, postoperative complications are
associated with reduced fitness. This study explored the relationship
between cardiorespiratory fitness variables derived by cardiopulmonary
exercise testing (CPET) and in‐hospital morbidity after major elective
colorectal surgery. Patients underwent preoperative CPETwith recording
of in‐hospital morbidity. Receiver operating characteristic (ROC)
curves and logistic regression were used to assess the relationship
between CPET variables and postoperative morbidity. Seven hundred and
three patients from six centres in the UK were available for analysis
(428 men, 275 women). ROCcurve analysis of oxygen uptake at estimated
lactate threshold (V˙o2at θ^L) and at peak exercise (V˙o2peak) gave an
area under the ROCcurve (AUROC) of 0·79 (95 per cent c.i. 0·76 to 0·83;
P< 0·001; cut‐off 11·1 ml per kg per min) and 0·77 (0·72 to 0·82; P<
0·001; cut‐off 18·2 ml per kg per min) respectively, indicating that
they can identify patients at risk of postoperative morbidity. In a
multivariable logistic regression model, selected CPETvariables and
body mass index (BMI) were associated significantly with increased odds
of in‐hospital morbidity (V˙o2at θ^L11·1 ml per kg per min or less:
odds ratio (OR) 7·56, 95 per cent c.i. 4·44 to 12·86, P< 0·001;
V˙o2peak18·2 ml per kg per min or less: OR2·15, 1·01 to 4·57, P =0·047;
ventilatory equivalents for carbon dioxide at estimated lactate
threshold (V˙E/V˙co2at θ^L) more than 30·9: OR1·38, 1·00 to 1·89, P
=0·047); BMIexceeding 27 kg/m2: OR1·05, 1·03 to 1·08, P< 0·001). A
laparoscopic procedure was associated with a decreased odds of
complications (OR0·30, 0·02 to 0·44; P =0·033). This model was able to
discriminate between patients with, and without in‐hospital morbidity
(AUROC0·83, 95 per cent c.i. 0·79 to 0·87). No adverse clinical events
occurred during CPET across the six centres. These data provide further
evidence that variables derived from preoperative CPETcan be used to
assess risk before elective colorectal surgery. Validated risk
assessment; (AN 38537189)