The Incidence and Outcomes of Major Limb Amputation in New Zealand from 2010 to 2021

Abstract

Background: Major limb amputation (MLA) can be a common outcome due to severe peripheral artery disease (PAD) and diabetic foot disease (DFD), and it carries a significant mortality burden. In New Zealand (NZ), there is little documentation of the incidence rate and mortality after MLA. The aim was to report the national crude and standardised rates and the mortality post MLA. Methods: This retrospective observational study included all MLAs that occurred within NZ from 1/1/2010 to 31/12/2021 due to DFD and/or PAD. Two national databases (National Minimum Dataset and the Australasian Vascular Audit) were utilised. The crude rates were calculated as cases per 100,000 in the NZ population per year including all ages (using the 2013 and 2018 NZ census figures). The age-standardised rates used the World Health Organization standard population. Post-operative mortality was calculated from the date of first hospitalisation for MLA. Results: From 2010 to 2021, there were 5293 MLA procedures in 4242 patients. On average, there were 8.5 MLAs per week and 441.1 MLAs annually. The overall crude rate was 9.44 per 100,000, and the standardised rate was 6.12 per 100,000. Over the 12 years, the crude rate decreased by 22% (p < 0.001), and the standardised rate decreased by 20.4% (p < 0.001). After MLA, the 30-day and 1-year mortality was 9.5% and 29.6%, respectively. From 2010 to 2021, the relative reduction in 30-day mortality was 45.1% (p < 0.001), and the reduction in 1-year mortality was 24.5% (p < 0.001). Increasing age, female sex and end-stage renal failure were predictors of 30-day and 1-year mortality. Conclusions: A considerable number of MLAs occur in NZ, with substantial perioperative mortality; however, the national incidence rates and mortality have improved over the last 12 years. This data might serve as benchmark to further reduce MLAs and improve patient outcomes.