Frailty scoring is moderately associated with cardiopulmonary exercise testing (CPET) performance in patients scheduled for major intra-abdominal surgery

Cardiopulmonary exercise testing (CPET) is an objective, dynamic measure of physiological function that informs shared decision making and guides peri-operative care of patients undergoing major intra-abdominal surgery. An anaerobic threshold < 11 ml.kg−1.min−1 and peak VO2 < 15 ml.kg−1.min−1 are common cut-points used in peri-operative risk assessment [1]. However, CPET is both costly and time consuming. Frailty scoring is a multidimensional patient evaluation that can identify markers of reduced physiological reserve. Routine pre-operative frailty assessment is recommended by the British Geriatric Society [2]. We hypothesised that frailty scores would identify patients with lower levels of cardiorespiratory fitness.MethodsWe conducted a service evaluation to compare existing frailty scoring systems and their components with CPET performance. We analysed patients age ≥ 65 years presenting to our CPET clinic prior to major elective intra-abdominal surgery over a 6-month period. Patients completed both the Edmonton Frail Scale (EFS) and Hopkins Frailty Score (HFS), which have both been validated in surgical populations [3]. Frailty scoring preceded CPET and followed the guidance of the original authors. Functional measures included grip strength and gait speed.ResultsData from 52 patients were analysed (23 male), mean age 74.7 years. The EFS identified 3/52 (6%) as frail. The HFS identified 7/52 (13%) with frailty. Mean EFS score was 3.32 (SD 2.47), mean HFS score was 1.27 (SD 1.22). Mean peak VO2 was 15.9 ml.kg−1.min−1 (5.4) and mean anaerobic threshold 11.6 ml.kg−1.min−1 (2.7). Anaerobic threshold did not correlate with either frailty scores but 37% (19/52) of patients had either an anaerobic threshold < 11.0 ml.kg−1.min−1 or were unable to manage a CPET. However, both frailty scores and their components had moderate but statistically significant correlation with peak VO2. The walking tests provided the best positive predictive value for peak VO2.imageFigure 1 ROC curves for predicting VO2 peak < 15 ml.kg−1.min−1 from the timed up and go test and 4 m walk test. AUC 0.87 – timed up and go test (95% CI 0.78–0.97, p < 0.01) and 0.83–4m walk test (95% CI 0.72–0.94, p < 0.01).DiscussionFrailty scores had moderate correlation with CPET performance. The frailty domains that assessed actual physical activity (timed up and go test and 4 m walk test) were better predictors of CPET performance. Further work is required to demonstrate whether these frailty tests are better than CPET in predicting postoperative outcomes after major surgery.References1. Struthers R, Erasmus P, Holmes K, et al. Assessing fitness for surgery: a comparison of questionnaire, incremental shuttle walk, and cardiopulmonary exercise testing in general surgical patients. British Journal of Anaesthesia 2008; 101: 774–80.2. Partridge JS, Harari D, Dhesi JK. Frailty in the older surgical patient: a review. Age and Ageing 2012; 41: 142–7.3. Revenig LM, Canter DJ, Taylor MD, et al. Too frail for surgery? Initial results of a large multidisciplinary prospective study examining preoperative variables predictive of poor surgical outcomes. Journal of the American College of Surgeons 2013; 217: 665–70.e1.