Association between neuraxial anaesthesia or general anaesthesia for lower limb revascularisation surgery in adults and clinical outcomes: population based comparative effectiveness study

OBJECTIVE To examine the associations between neuraxial anaesthesia or general anaesthesia and clinical outcomes, length of hospital stay, and readmission in adults undergoing lower limb revascularisation surgery. DESIGN Comparative effectiveness study using linked, validated, population based databases. SETTING Ontario, Canada, 1 April 2002 to 31 March 2015. PARTICIPANTS 20 988 patients Ontario residents aged 18 years or older who underwent their first lower limb revascularisation surgery in hospitals performing 50 or more of these surgeries annually. MAIN OUTCOME MEASURES Primary outcome was 30 day all cause mortality. Secondary outcomes were in-hospital cardiopulmonary and renal complications, length of hospital stay, and 30 day readmissions. Multivariable, mixed effects regression models, adjusting for patient, procedural, and hospital characteristics, were used to estimate associations between anaesthetic technique and outcomes. Robustness of analyses were evaluated by conducting instrumental variable, propensity score matched, and survival sensitivity analyses. RESULTS Of 20 988 patients who underwent lower limb revascularisation surgery, 6453 (30.7%) received neuraxial anaesthesia and 14 535 (69.3%) received general anaesthesia. The percentage of neuraxial anaesthesia use ranged from 0.6% to 90.6% across included hospitals. Furthermore, use of neuraxial anaesthesia declined by 17% over the study period. Death within 30 days occurred in 204 (3.2%) patients who received neuraxial anaesthesia and 646 (4.4%) patients who received general anaesthesia. After multivariable, multilevel adjustment, use of neuraxial anaesthesia compared with use of general anaesthesia was associated with decreased 30 day mortality (absolute risk reduction 0.72%, 95% confidence interval 0.65% to 0.79%; odds ratio 0.68, 95% confidence interval 0.57 to 0.83; number needed to treat to prevent one death=139). A similar direction and magnitude of association was found in instrumental variable, propensity score matched, and survival analyses. Use of neuraxial anaesthesia compared with use of general anaesthesia was also associated with decreased in-hospital cardiopulmonary and renal complications (odds ratio 0.73, 0.63 to 0.85) and a reduced length of hospital stay (-0.5 days,-0.3 to-0.6 days). CONCLUSIONS Use of neuraxial anaesthesia compared with general anaesthesia for lower limb revascularisation surgery was associated with decreased 30 day mortality and hospital length of stay. These findings might have been related to reduced cardiopulmonary and renal complications after neuraxial anaesthesia and support the increased use of neuraxial anaesthesia in patients undergoing these surgeries until the results of a large, confirmatory randomised trial become available.