Association of Anesthesia Technique With Morbidity and Mortality in Patients With COVID-19 and Surgery for Hip Fracture: a Retrospective Population Cohort Study

Background: Patients with hip fracture have poor outcomes, attributed to risk factors that include advanced age and higher rates of underlying chronic comorbidities. COVID-19 infection is an independent risk factor for increased mortality in hip fracture patients in the perioperative period. A recent meta-analysis demonstrates COVID-19 infection is associated with higher than seven-fold increase in risk of mortality. Recommended management of hip fracture includes timely surgical repair, multimodal pain control, and multidisciplinary follow-up, to facilitate return to mobility and independent function.

Anesthesia for hip fracture surgery can be achieved by either general anesthesia (GA) or spinal anesthesia (SA). The potential advantages of SA include opioid-sparing effects, lessened impacts on the respiratory and gastrointestinal systems, and reduction in rates of adverse outcomes such as pneumonia, mechanical ventilation, intensive care unit (ICU) admission, venous thromboembolism (VTE), myocardial infarction (MI), stroke, transfusion, readmission, and prolonged postoperative length of stay. However, a recent randomized control trial found no difference between SA and GA for older adults undergoing hip fracture surgery for the primary outcome of survival and recovery of ambulation at 60 days.

While emerging evidence shows COVID-19 infection increases mortality after hip surgery, there is a lack of research examining whether the choice of anesthetic technique modifies the postoperative mortality and morbidity of hip fracture patients with COVID-19 infection. This is particularly important due to the high mortality (35% in COVID-positive patients, vs. 2% in patients without COVID), with the potential for SA to modify this risk by circumventing the need for airway interventions. SA may also offer superiority over general anesthesia for limiting aerosol generation and exposure of operating room staff during the pandemic. While SA may reduce the risk of pulmonary morbidity by reducing the need for airway interventions, its motor block on accessory muscles and the need for sedation may adversely impact ventilation. Investigators hypothesize that spinal anesthesia (SA) is associated with decreased mortality compared to general anesthesia (GA) for patients undergoing hip fracture surgery.

Study Design: The requirement for written informed consent will be waived for use of deidentified data. Patient information will be obtained for the retrospective cohort analysis using the NSQIP® (general dataset linked with the Hip Fracture Procedure Targeted Dataset), a prospectively-collected multicentre dataset with more than 150 clinical variables within 30 days after surgery. The setting of this study will be patient data obtained from the multicentre generated NSQIP Hip Fracture Procedure Targeted Dataset. The period of patient data obtained will include from January 2017 through December 2021. We will omit the data from January 2020 to December 2020 given there was no reporting of COVID status during this period. Data will only be obtained from patients undergoing hip surgery with mortality and morbidity gathered for 30 days postoperatively. In this study, the investigators goal is to evaluate the adjusted association between anesthesia technique and mortality and morbidity after hip fracture surgery for patients who tested positive for COVID-19.

The primary objective is to determine for patients undergoing hip surgery with COVID-19 infection, whether SA, as compared to GA, is associated with a lower rate of mortality 30 days postoperatively.