Outcome by mode of anaesthesia for hip fracture surgery. An observational audit of 65 535 patients in a national dataset

Abstract

Large observational studies of accurate data can provide similar results to more arduous and expensive randomised controlled trials. In 2012, the National Hip Fracture Database extended its dataset to include 'type of anaesthesia' data fields. We analysed 65 535 patient record sets to determine differences in outcome. Type of anaesthesia was recorded in 59 191 (90%) patients. Omitting patients who received both general and spinal anaesthesia or in whom an uncertain type of anaesthesia was recorded, there was no significant difference in either cumulative five-day (2.8% vs 2.8%, p = 0.991) or 30-day (7.0% vs 7.5%, p = 0.053) mortality between 30 130 patients receiving general anaesthesia and 22 999 patients receiving spinal anaesthesia, even when 30-day mortality was adjusted for age and ASA physical status (p = 0.226). Mortality within 24 hours after surgery was significantly higher among patients receiving cemented compared with uncemented hemiarthroplasty (1.6% vs 1.2%, p = 0.030), suggesting excess early mortality related to bone cement implantation syndrome. If these data are accurate, then either there is no difference in 30-day mortality between general and spinal anaesthesia after hip fracture surgery per se, and therefore future research should focus on how to make both types of anaesthesia safer, or there is a difference, but mortality is not the correct outcome to measure after anaesthesia, and therefore future research should focus on differences between general and spinal anaesthesia. These could include more anaesthesia-sensitive outcomes, such as hypotension, pain, postoperative confusion, respiratory infection and mobilisation.