Outcome differences after elective or emergency hip operations

In their retrospective analysis of of 65 535 patients having hip fracture surgery White et al. found no mortality difference according to anaesthetic technique 1. This is a reassuring finding, suggesting either that anaesthetists are matching their techniques to their patients, or that there is equivalent mortality between these modes of anaesthesia. However, if it is the latter, White et al.'s data are discordant with similar recent studies into elective lower limb orthopaedic surgery, which suggest that spinal anaesthesia is associated with lower mortality 2, wound infection 3, 4, and transfusion rates 4. Can the authors offer any explanation why neuroaxial anaesthesia might be beneficial in elective orthopaedic surgery, a lower-risk procedure with selected and optimised patients, but not (apparently) in similar emergency procedures?