Jason K Gurney, James Stanley, Juliet Rumball-Smith, Steve York, Diana Sarfati

The objectives of this study were to 1) describe postoperative mortality after lower-limb amputation in a national prevalent cohort of patients with diabetes, and 2) investigate whether postoperative mortality differs by demographic subgroup, patient morbidity level, and health system factors related to the facility in which the amputation occurred. A national prevalent cohort of 302,339 individuals diagnosed with diabetes between 2005 and 2014 were followed until the end of 2014 for major and minor lower-limb amputation and subsequent postoperative mortality by using national health data collections. Kaplan-Meier survival analysis was used to determine postoperative survival, whereas Cox proportional hazards models were used to describe the relative hazard of postoperative mortality, adjusted for covariates. A total of 6,352 lower-limb amputations occurred over the study period (2,570 major amputations, 3,782 minor amputations). More than 11% of patients who underwent major amputation died within 30 days, whereas nearly 18% died within 90 days. Death was most common among older patients and indigenous Māori. Sex, deprivation, rurality, hospital volume, admission type, and patient comorbidity were not consistently or substantially independently associated with risk of postoperative mortality. In a national prevalent cohort of patients with diabetes, there was high risk of postoperative mortality as well as a differential risk of postoperative mortality by demographic subgroup. Further work is required to investigate the drivers of postoperative mortality among patients with diabetes who undergo amputation.