New Australian research has, for the first time, looked at geographical variations in amputation incidence in Australia. Using data from the Australian Institute of Health and Welfare, researchers from La Trobe University, Federation University and the University of New South Wales looked at all amputations in Australia for the financial years 2007-8 to 2011-12. In addition to incidence rates in the different states and territories, the researchers also investigated risk factors in each region.
To reach their answers, the researchers had to analyse the 35,306 amputations performed in those years. An enormous amount of work, resulting in an impressive dataset. Of these amputations, 40% were toe amputations, 30% partial foot, 16% transtibial and 12% transfemoral amputations. As expected, the majority of people undergoing amputation were old, and about half had diabetes. The national incidence rate was 32.4 per 100,000 population. Unfortunately, no diabetes specific incidence rate was provided.
A region-by-region comparison showed minor differences between the states and territories, with the exception of the Northern Territory (NT). In the NT, incidence rates were almost twice as high. Further, almost 80% of the amputations occurred in people with diabetes in the NT, compared to the 50% in the rest of Australia, and people were a lot younger at time of amputation.
Compared to the baseline year of 2007-8, incidence rates showed a consistent and significant reduction in WA, the NT and the ACT. The influence of risk factors varied between regions, and resulted in complex interactions. For example, in the NT, type 2 diabetes was associated with an increase in relative risk, but this was confounded by age.
This first study to look at geographical differences in Australian amputation rates presents a significant and important piece of work. At the same time, it also poses more questions than answers. We may expect similarly large differences in the incidence rates within states, for example between their rural and remote and metropolitan areas. In the seminal UK geographical variation study, geographic regions were much smaller, allowing for more detailed comparison. With the myriad of factors influencing amputation (person, disease and health care organization related), and the statistical and privacy limitations as described by the authors, it remains to be seen whether these questions can be answered in the short-term. However, if we are to end avoidable amputations in a generation, such insights followed by region-specific approaches to tackle the problem are very much needed.
While this paper may not change daily clinical practice today, the high incidence rates in the NT point at the importance of more prevention and treatment improvement in that territory. At the same time, we hope that more research using this impressive database and following the great deal of work to set up this study will follow in the coming years, to better inform our choices.