The Inter-operator Variability in Determining the Anaerobic Threshold (AT) after Pre-operative Cardiopulmonary Exercise Testing (CPET)

Abstract

Introduction: The use of pre-operative CPET has been well defined. Previous studies have identified a relationship between CPET parameters and post-operative outcomes. The aim of this study was to assess the inter-operator variability in determining the AT after pre-operative CPET and the impact it may have on patient risk stratification. Methods: The AT of patients who were referred for preoperative CPET were determined by two healthcare professionals (HCP). The HCP9s were blinded to each others AT’s for the duration of data collection. Bland Altman and linear regression analysis determined the inter-operative agreement between the HCP9s. Results: In total, 29 consecutive AT’s were analysed by two HCP9s. Linear regression analysis showed a correlation coefficient, r2 value of 0.914 (Figure 1). Bland-Altman analysis showed a mean difference of -0.02 percentage points with 95% confidence internal (CI) -0.5 to 0.46. There was only 1 patient with an AT outside 2SD, which may have had a clinical impact on risk stratification ( 11ml.min.kg to determine low – high surgical risk, 11.7ml.min.kg vs. 10.4ml.min.kg). Conclusion: This study shows that within this small single centre cohort there is a high agreement between two HCP9s measuring the AT by the ‘gold standard’ V-Slope method. Future, larger, multicentre studies would be required to further substantiate this study.