Geographic variation in amputation rates among patients with diabetes and/or peripheral arterial disease in the rural state of West Virginia identifies areas for improved care

Objective: Amputation is a devastating but preventable complication of diabetes and peripheral arterial disease (PAD). Multiple studies have focused on disparities in amputation rates based on race and socioeconomic status, but few focus on amputation trends in rural populations. The objective of this study was to identify the prevalence of major and minor amputation among patients admitted with diabetes and/or PAD in a rural, Appalachian state, and to identify geographic areas with higher than expected major and minor amputations using advanced spatial analysis while controlling for comorbidities and rurality. Methods: Patient hospital admissions of West Virginia residents with diagnoses of diabetes and/or PAD and with or without an amputation procedure were identified from the West Virginia Health Care Authority State Inpatient Database from 2011 to 2016 using relevant International Classification of Diseases, 9th edition and 10 the edition codes. Bayesian spatial hierarchical modeling was conducted to identify areas of high risk, while controlling for important confounders for amputation. Results: Overall, there were 5557 amputations among 459,452 hospital admissions with diabetes and/or PAD from 2011 to 2016. The majority of the amputations were minor (61.7%; n = 3430), with a prevalence of 7.5 per 1000 and 40.4% (n = 2248) were major, with a prevalence of 4.9 per 1000. Geographic analysis found significant variation in risk for both major and minor amputation across the state, even after adjusting for the prevalence of risk factors. Analyses indicated an increased risk of amputation in the central and northeastern regions of West Virginia at the county level, although zip code-level patterns of amputation varied, with high-risk areas identified primarily in the northeastern and south central regions of the state. Conclusions: There is significant geographic variation in risk of amputation across West Virginia, even after adjusting for disease-related risk factors, suggesting priority areas for further investigation. The level of granularity obtained using advanced spatial analyses rather than traditional methods demonstrate the value of this approach, particularly when risk estimates are used to inform policy or public health intervention.