The Intrarater and Interrater Reliability of Measures Derived from Cardiopulmonary Exercise Testing in Patients with Abdominal Aortic Aneurysms

Abstract

Patients with abdominal aortic aneurysms (AAAs) often have low exercise tolerance due to comorbidities and advanced age. Cardiopulmonary exercise testing (CPET) is predictive of postoperative morbidity and mortality in patients with AAA. We aimed to assess the intrarater and interrater reliability of both treadmill-based and cycle ergometer-based CPET variables. Patients with an AAA (>3.5cm) were randomized to a treadmill or bike CPET. Patients were asked to perform two separate CPETs seven days apart after a familiarization protocol. All CPETs were carried out using a ramp cycle or modified Bruce treadmill protocol with breath-by-breath gas analysis. Twenty-two male and 2 female patients, aged 73.6±6.0 years, completed the study. Intrarater analysis (intraclass correlation coefficients) demonstrated high reliability on both the treadmill and bike for ventilatory anaerobic threshold (r=0.834 and r=0.975, respectively). All other CPET variables demonstrated high intrarater reliability on both modalities, bar the highest point for the ventilatory slope of oxygen (VE/VO2) on the treadmill (substantial agreement r=0.755). Furthermore, interrater reliability demonstrated high agreement for ventilatory anaerobic threshold on both the treadmill and cycle (r=0.983 and r=0.905, respectively). All other CPET variables demonstrated high intrarater reliability on both modalities, with the exception of VO2Peak on the cycle ergometer (fair agreement r=0.400). CPET in patients with AAAs is a reliable tool test and among CPET test reviewers for common testing modalities/protocols. These findings provide further support for the use of CPET, especially treadmill walking, as a clinical measure of perioperative cardiorespiratory fitness in patients with AAAs.