Added value of subjective assessed functional capacity before non-cardiac surgery in predicting postoperative myocardial injury

Abstract

Background: Functional capacity is used as an indicator for cardiac testing before non-cardiac surgery and is often performed subjectively. However, the value of subjectively estimated functional capacity in predicting cardiac complications is under debate. We determined the predictive value of subjectively assessed functional capacity on postoperative cardiac complications and mortality. Design: An observational cohort study in patients aged 60 years and over undergoing elective inpatient non-cardiac surgery in a tertiary referral hospital. Methods: Subjective functional capacity was determined by anaesthesiologists. The primary outcome was postoperative myocardial injury. Secondary outcomes were postoperative inhospital myocardial infarction and one year mortality. Logistic regression analysis and area under the receiver operating curves were used to determine the added value of functional capacity. Results: A total of 4879 patients was included; 824 (17%) patients had a poor subjective functional capacity. Postoperative myocardial injury occurred in 718 patients (15%). Poor functional capacity was associated with myocardial injury (relative risk (RR) 1.7, 95% confidence interval (CI) 1.5-2.0; P < 0.001), postoperative myocardial infarction (RR 2.9, 95% CI 1.9-4.2; P < 0.001) and one year mortality (RR 1.7, 95% CI 1.4-2.0; P < 0.001). After adjustment for other predictors, functional capacity was still a significant predictor for myocardial injury (odds ratio (OR) 1.3, 95% CI 1.0-1.7; P = 0.023), postoperative myocardial infarction (OR 2.0, 95% CI 1.3-3.0; P = 0.002) and one year mortality (OR 1.4, 95% CI 1.1-1.8; P = 0.003), but had no added value on top of other predictors. Conclusions: Subjectively assessed functional capacity is a predictor of postoperative myocardial injury and death, but had no added value on top of other preoperative predictors.