Patients' inability to perform a preoperative cardiopulmonary exercise test or demonstrate an anaerobic threshold is associated with inferior outcomes after major colorectal surgery

Background. Surgical patients with poor functional capacity, determined by oxygen consumption at anaerobic threshold (AT) during cardiopulmonary exercise testing (CPET), experience longer hospital stays and worse short- and medium-term survival. However, previous studies excluded patients who were unable to perform a CPET or who failed to demonstrate an AT. We hypothesized that such patients are at risk of inferior outcomes after elective surgery. Methods. All patients undergoing major colorectal surgery attempted CPET to assist in the planning of care. Patients were stratified by their test results into Fit (AT >= 11.0 ml O-2 kg(-1) min(-1)), Unfit (AT < 11.0 ml O-2 kg(-1) min(-1)), or Unable to CPET groups (failed to pedal or demonstrate an AT). For each group, we determined hospital stay and mortality. Results. Between March 2009 and April 2010, 269 consecutive patients were screened, and proceeded to bowel resection. Median hospital stay was 8 days (IQR 5.1-13.4) and there were 44 deaths (16%) at 2 yr; 26 (9.7%) patients were categorized as Unable to CPET, 69 (25.7%) Unfit and 174 (64.7%) Fit. There were statistically significant differences between the three groups in hospital stay [median (IQR) 14.0 (10.5-23.8) vs 9.9 (5.5-15) vs 7.1 (4.9-10.8) days, P< 0.01] and mortality at 2 yr [11/26(42%) vs 14/69 (20%) vs 19/174 (11%), respectively (P < 0.01)] although the differences between Unable and Unfit were not statistically different. Conclusions. Patients' inability to perform CPET is associated with inferior outcomes after major colorectal surgery. Future studies evaluating CPET in risk assessment for major surgery should report outcomes for this subgroup.