PC082. High-Granularity Geographic Information System Analysis of Amputation Trends in West Virginia Identifies Specific Geographic Areas to Target for Improved Diabetes and Peripheral Artery Disease Care

Abstract

Amputation is a devastating but preventable complication of diabetes and peripheral artery disease (PAD). Multiple studies have focused on disparities in amputation rates based on race/ethnicity and socioeconomic status, but few focus on amputation trends in rural populations. This study’s objective was to identify the prevalence of major and minor amputation among those with documented disease in a rural Appalachian state and to use advanced spatial epidemiology methods to identify high-risk areas for amputation. This study used 2011 to 2016 hospital discharge data from the West Virginia State Inpatient Database to identify all adults (>18 years) with recorded diagnoses of diabetes or PAD. Major and minor amputations in this population were identified using International Classification of Diseases, Ninth Revision and Tenth Revision codes. Amputation rate was defined as the number of amputations among admissions with diabetes or PAD. To identify high-risk areas for amputation, Bayesian spatial hierarchical modeling was conducted to obtain model-fitted relative risk estimates at both the county and ZIP code level (of patient residence), and the deviance information criterion was used to investigate model performance. In 2011 to 2016, there were 519,990 admissions that met the criteria of diabetes or PAD. Among them, 2584 major and 3829 minor amputations were performed, with 6279 amputations performed overall, corresponding to a rate of 12.1/1000. This number is significantly higher than the national average of 2.4/1000 reported in other studies. On geographic analysis, we found significant variation in risk for both major and minor amputation across the state, even after adjusting for the prevalence of risk factors. Specifically, we found that ZIP codes in central and northeastern West Virginia had relative risks of amputation >1.5 times higher than the rest of the state (Figs 1 and 2). In addition, we found significant differences in estimates between standard crude risk estimation for this disease and our method, which was able to illustrate amputation risk at a much higher level of granularity by producing ZIP code-level data on amputation risk while controlling for associated comorbidities. We found a significantly higher prevalence of amputation in West Virginia compared with the national prevalence reported in other studies. In addition, we found significant geographic variation in amputation risk across the state and identified highly specific areas where, even after adjusting for covariates, the risk of amputation among those with diabetes or PAD was higher than expected. These findings allow the targeted allocation of resources for amputation prevention efforts and also direct further research to gain a greater understanding of the cause of this issue.Fig 2Geographic variation in model-fitted estimates of ZIP code-level relative risk of minor amputation in West Virginia, 2011 to 2016.View Large Image Figure ViewerDownload Hi-res image Download (PPT)