Association of echocardiography before major elective non-cardiac surgery with postoperative survival and length of hospital stay: population based cohort study

OBJECTIVE: To determine the association of resting echocardiography before elective intermediate to high risk non-cardiac surgery with survival and length of hospital stay. DESIGN: Population based retrospective cohort study. SETTING: Acute care hospitals in Ontario, Canada, between 1 April 1999 and 31 March 2008. PARTICIPANTS: Patients aged over 40 years who had elective intermediate to high risk non-cardiac surgery. INTERVENTION: Resting echocardiography within 6 months before surgery. MAIN OUTCOME MEASURES: Postoperative survival (30 days and 1 year) and length of hospital stay; postoperative surgical site infection as an outcome for which no association with echocardiography would be expected. RESULTS: Of the 264,823 patients in the entire cohort, 15.1% (n = 40,084) had echocardiography. After use of propensity score methods to assemble a matched cohort (n = 70,996) that reduced differences between patients who had or had not had echocardiography, echocardiography was associated with increases in 30 day mortality (relative risk 1.14, 95% confidence interval 1.02 to 1.27), 1 year mortality (1.07, 1.01 to 1.12), and length of hospital stay but no difference in surgical site infections (1.03, 0.98 to 1.06). The association with mortality was influenced (P = 0.02) by whether patients had had stress testing or had risk factors for cardiac complications. No association existed between echocardiography and mortality among patients who had stress testing (relative risk 1.01, 0.92 to 1.11) or among patients at high risk who had not had stress testing (1.00, 0.87 to 1.13). However, echocardiography was associated with mortality in patients at low risk (relative risk 1.44, 1.14 to 1.82) and intermediate risk (1.10, 1.02 to 1.18) who had not had stress testing. CONCLUSIONS: Preoperative echocardiography was not associated with improved survival or shorter hospital stay after major non-cardiac surgery. These findings highlight the need for further research to guide better use of this common preoperative test.