Geographic Variation of the Incidence Rate of Lower Limb Amputation in Australia from 2007-12

PLOS ONE, Dec 2019

In Australia, little is known about how the incidence rate (IR) of lower limb amputation (LLA) varies across the country. While studies in other economically developed countries have shown considerable geographic variation in the IR-LLA, mostly these have not considered whether the effect of common risk factors are the same across regions. Mapping variation of the IR-LLA, and the effect of common risk factors, is an important first step to focus research into areas of greatest need and support the development of regional specific hypotheses for in-depth examination. The aim of this study was to describe the geographic variation in the IR-LLA across Australia and understand whether the effect of common risk factors was the same across regions. Using hospital episode data from the Australian National Hospital Morbidity database and Australian Bureau of Statistics, the all-cause crude and age-standardised IR-LLA in males and females were calculated for the nation and each state and territory. Generalised Linear Models were developed to understand which factors influenced geographic variation in the crude IR-LLA. While the crude and age-standardised IR-LLA in males and females were similar in most states and territories, they were higher in the Northern Territory. The effect of older age, being male and the presence of type 2 diabetes was associated with an increase of IR-LLA in most states and territories. In the Northern Territory, the younger age at amputation confounded the effect of sex and type 2 diabetes. There are likely to be many factors not included in this investigation, such as Indigenous status, that may explain part of the variation in the IR-LLA not captured in our models. Further research is needed to identify regional- and population- specific factors that could be modified to reduce the IR-LLA in all states and territories of Australia.

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Geographic Variation of the Incidence Rate of Lower Limb Amputation in Australia from 2007-12

January Geographic Variation of the Incidence Rate of Lower Limb Amputation in Australia from 2007-12 Michael P. Dillon 1 2 3 Lauren V. Fortington 1 3 Muhammad Akram 0 1 3 Bircan Erbas 1 3 Friedbert Kohler 1 3 4 0 Australian Centre of Health and Social Research, Australian Catholic University , Melbourne, Victoria , Australia , 4 School of Psychology and Public Health, La Trobe University , Bundoora, Victoria , Australia 1 Funding: This research was funded by APC Prosthetics Pty Ltd. , New South Wales. Australia 2 School of Allied Health, La Trobe University , Bundoora, Victoria , Australia , 2 Australian Collaboration for Research into Injury in Sports and its Prevention, Federation University , Ballarat, Victoria , Australia 3 Editor: Wataru Nishimura, Jichi Medical University , JAPAN 4 Rehabilitation Medicine, Braeside Hospital , Prairiewood, New South Wales , Australia , 6 Faculty of Medicine, University of New South Wales , Kensington, New South Wales , Australia In Australia, little is known about how the incidence rate (IR) of lower limb amputation (LLA) varies across the country. While studies in other economically developed countries have shown considerable geographic variation in the IR-LLA, mostly these have not considered whether the effect of common risk factors are the same across regions. Mapping variation of the IR-LLA, and the effect of common risk factors, is an important first step to focus research into areas of greatest need and support the development of regional specific hypotheses for in-depth examination. The aim of this study was to describe the geographic variation in the IR-LLA across Australia and understand whether the effect of common risk factors was the same across regions. Using hospital episode data from the Australian National Hospital Morbidity database and Australian Bureau of Statistics, the all-cause crude and age-standardised IR-LLA in males and females were calculated for the nation and each state and territory. Generalised Linear Models were developed to understand which factors influenced geographic variation in the crude IR-LLA. While the crude and age-standardised IR-LLA in males and females were similar in most states and territories, they were higher in the Northern Territory. The effect of older age, being male and the presence of type 2 diabetes was associated with an increase of IR-LLA in most states and territories. In the Northern Territory, the younger age at amputation confounded the effect of sex and type 2 diabetes. There are likely to be many factors not included in this investigation, such as Indigenous status, that may explain part of the variation in the IR-LLA not captured in our models. Further research is needed to identify regional- and population- specific factors that could be modified to reduce the IR-LLA in all states and territories of Australia. - Data Availability Statement: Data were provided by the Australian Institute of Health and Welfare with the approval of each Australian state and territory health authority. Given the conditions of the approval, we are unable to make the complete data available. Requests for these data can be made to the Australian Institute of Health and Welfare, Hospitals Data Unit via an online request: http://www.aihw.gov.au/custom-data-requestservice/. http://apcprosthetics.com.au/ Funds were awarded to MD, FK and BE. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Introduction In Australia, there are some 8000 lower limb amputations (LLA) performed annually [ 1,2 ]. Despite a variety of targeted interventions, such as the increased availability of high-risk foot clinics and clear guidelines for their delivery[3], there has not been a reduction in the incidence rate of lower limb amputation (IR-LLA) at a national level [ 2 ]. While data describing the IR-LLA is available at a national level [ 2 ] and for isolated states [ 4,5 ], there are no studies that describe the IR-LLA for all Australian states and territories, and whether this has changed over time. Similarly, there are no studies that quantify whether the effect of common risk factors such as sex, age or the presence of diabetes are similar across different geographic regions. Research in similar, economically-developed, countries has shown considerable geographic variation in the IR-LLA[6±10]. Synthesis of these investigations suggests that it is common for the IR-LLA to be two-three times higher in some regions compared to others. Such geographic variation in the IR-LLA may reflect that common risk factors for LLA are not equally distributed across the population, but rather geographically clustered. Researchers have suggested considerable variation in the geographic distribution of LLAs based on age, sex, diabetes, socioeconomic- and Indigenous- status, as well as remoteness [7,10±12]. Variations in healthcare between regions are also common [ 10 ] as e (...truncated)


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Michael P. Dillon, Lauren V. Fortington, Muhammad Akram, Bircan Erbas, Friedbert Kohler. Geographic Variation of the Incidence Rate of Lower Limb Amputation in Australia from 2007-12, PLOS ONE, 2017, Volume 12, Issue 1, DOI: 10.1371/journal.pone.0170705