Cardiopulmonary exercise testing predicts 5 yr survival after major surgery.
BACKGROUND
Cardiopulmonary exercise testing (CPET) is used to assess perioperative risk in surgical patients. While previous studies have looked at short-term outcomes, this paper explores the ability of CPET to predict 5 yr survival after major surgery.


METHODS
Over a period (1996-2009), 1725 patients referred for CPET subsequently underwent major surgery. Breath-by-breath data derived during each patient's CPET was processed using customized software to extract variables likely to impact on survival. Initial analysis examined the predictive power of single variables. Subsequently, Bayesian model averaging (BMA) was used to construct a multivariate model defining the association between CPET data and 5 yr survival.


RESULTS
Six hundred and sixteen (36%) of the study patients died. Single variables were not significantly associated with 5 yr postoperative survival. BMA indicated the following major predictors of 5 yr survival: patient gender; type of surgery, and forced vital capacity. Four variables derived at the patient's anaerobic threshold were weaker predictors. These were end-tidal oxygen concentration, respiratory exchange ratio, oxygen consumption per unit body weight, and oxygen consumption per heart beat. The resulting model was then used to divide patients into low-, medium-, or high-risk categories, and 5 yr survival for each category was 87.8; 75.8, and 53.8% respectively. Survival was independent of patient age.


CONCLUSIONS
Multivariate analysis and model generation techniques can be applied to CPET data to predict 5 yr survival after major surgery more accurately than is possible with single variable analysis.
Department of Anaesthesia, The Geelong Hospital, Ryrie Street, Geelong, VIC 3220, Australia. markcolsonline@gmail.com
M
M
Colson
J
J
Baglin
S
S
Bolsin
M P W
MP
Grocott
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005080:Exercise Test / Q000379:methods* / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D011183:Postoperative Complications / Q000175:diagnosis* / Q000401:mortality; D011237:Predictive Value of Tests; D012372:ROC Curve; D018570:Risk Assessment / Q000379:methods / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity; D017678:Sex Distribution; D013514:Surgical Procedures, Operative / Q000401:mortality*; D016019:Survival Analysis; D016896:Treatment Outcome; D014797:Vital Capacity