Supplementary Material for: The Steep Ramp Test as Precursor to Assess Physical Fitness Before Esophagectomy in Cancer Patients

Abstract Background Maximum oxygen uptake (VO₂max) is a predictor for postoperative complications after esophagectomy. Cardiopulmonary Exercise Test (CPET) is the golden standard for measuring VO₂max. The alternative Steep Ramp Test (SRT) is less strenuous with several benefits, providing an estimation of VO₂max. This study aims to determine whether SRT is a reliable alternative for CPET to evaluate preoperative fitness. Methods A total of 113 patients were included in this study. The agreement between SRT and CPET was analyzed using a t-test, Intraclass Correlation Coefficient (ICC), and the Bland-Altmann analysis. The threshold for adequate preoperative fitness was set at 17.0 ml/kg/min Results The mean difference between CPET and SRT was 2.77 ml/kg/min (95% CI 2.14–3.41). The ICC was 0.79 (95% CI 0.70-0.85). The upper limit of agreement of the Bland-Altmann was 9.44. The addition of 9.44 to the CPET-threshold gives an SRT-threshold of 26.44 ml/kg/min. Thirty-one (27.4%) patients scored higher than the SRT-threshold. Conclusion The SRT VO2max differs from VO₂max as measured by CPET. However, the difference was found to be clinically irrelevant for a substantial portion of patients. Hence, SRT is a promising alternative to CPET for determining physical fitness, and might render CPET obsolete for fit individuals.