Geographic variation in Medicare spending and mortality for diabetic patients with foot ulcers and amputations

https://doi.org/10.1016/j.jdiacomp.2012.09.003Get rights and content

Abstract

Aims

The purpose of this study was to identify the presence or absence of geographic variation in Medicare spending and mortality rates for diabetic patients with foot ulcers (DFU) and lower extremity amputations (LEA).

Methods

Diabetic beneficiaries with foot ulcers (n=682,887) and lower extremity amputations (n=151,752) were enrolled in Medicare Parts A and B during the calendar year 2007. We used ordinary least squares (OLS) regression to explain geographic variation in per capita Medicare spending and one-year mortality rates.

Results

Health care spending and mortality rates varied considerably across the nation for our two patient cohorts. However, higher spending was not associated with a statistically significant reduction in one-year patient mortality (P= .12 for DFU, P= .20 for LEA). Macrovascular complications for amputees were more common in parts of the country with higher mortality rates (P< .001), but this association was not observed for our foot ulcer cohort (P= .12). In contrast, macrovascular complications were associated with increased per capita spending for beneficiaries with foot ulcers (P= .01). Rates of hospital admission were also associated with higher per capita spending and increased mortality rates for individuals with foot ulcers (P< .001 for health spending and mortality) and lower extremity amputations (P< .001 for health spending, P= .01 for mortality).

Conclusions

Geographic variation in Medicare spending and mortality rates for diabetic patients with foot ulcers and amputations is associated with regional differences in the utilization of inpatient services and the prevalence of macrovascular complications.

Introduction

The number of Medicare patients with diabetes is expected to nearly double over the next twenty years as a result of obesity trends and an aging population (Harris et al., 1998, Helmrich et al., 1991, Kannel et al., 1979, Lee et al., 2010, National Diabetes Statistics, 2011, Sloan et al., 2008, Wang et al., 2011, Wild et al., 2004, Wilson et al., 1981, Zimmet et al., 2001). Future growth in disease prevalence will act as a catalyst for rising health care costs, for which diabetes and its complications currently account for 1 out of every 10 health care dollars spent in the United States annually (American Diabetes Association, 2008).

Currently, the medical management of diabetes varies considerably across the country with certain regions favoring one drug class over another (Sargen, Hoffstad, Wiebe, & Margolis, 2012). Additionally, Medicare reimbursements for diabetic patients also exhibit marked geographic variation. Despite these regional differences in diabetes management and Medicare spending, it is unknown if higher per capita spending results in improved patient survival.

Diabetic patients with foot ulcers and lower extremity amputations are particularly expensive to treat. Beneficiaries with chronic wounds account for 10% of the entire diabetic Medicare population and are responsible for a fourfold increase in annual per capita health care expenditures compared to diabetic patients without these complications (Margolis et al., 2011b). In this study, our primary objective was to determine if there is geographic variation in Medicare spending and mortality rates for diabetic patients with foot ulcers and lower extremity amputations and to evaluate if higher per capita spending regions are associated with improved patient survival. We also perform linear regression analysis to determine the effect that disease severity (rates of macrovascular and microvascular complications) and the utilization of inpatient and outpatient services (hospital admission rates and outpatient visits) have on per capita expenditures and mortality rates within a geographic region. These associations represent potential targets for clinical and health policy interventions that can reduce healthcare costs and improve patient outcomes.

Section snippets

Study population

Our study population included all patients enrolled in Medicare Parts A and B for the calendar year 2007 (n=8.4 million). For this study, beneficiaries were considered alive up to and including the month of their death. Enrollment was determined using the Medicare Enrollment Database. Individuals were determined to have diabetes if they had two or more ICD-9 (International Classification of Diseases, 9th Revision) codes or one ICD-9 inpatient claim consistent with such a diagnosis, a method

Results

There were 8,430,700 individuals with diabetes enrolled in Medicare Parts A and B during the calendar year 2007. The number of patients with diabetic foot ulcers and lower extremity amputations was 682,887 and 151,752, respectively. Medical expenditures for diabetic enrollees varied more than two-fold between referral regions for each patient cohort (Fig. 1). Per capita health care spending was significantly higher for beneficiaries with foot ulcers ($31,363, 95% CI: $30,711–$32,015) and lower

Discussion

The growing prevalence of diabetes amongst Americans over the age of 65 will significantly increase Medicare spending in future years. Although beneficiaries with foot ulcers and amputations represent only 10% of all diabetic Medicare beneficiaries, they are very expensive to treat accounting for 24.4% of total health care expenditures for this diabetic population.

In this study, we found that per capita Medicare spending and mortality rates varied considerably between hospital referral regions.

Conclusions

Our analysis reveals significant geographic variation in Medicare spending and mortality rates for diabetic patients with foot ulcers and lower extremity amputations. Local differences in hospital admission rates and the prevalence of macrovascular complications are associated with geographic variation in spending and mortality. It will be critically important for physicians and health policy planners to direct resources in future years towards preventing macrovascular complications and

Acknowledgments

David Margolis and Michael Sargen had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. The authors have no relevant conflicts of interest concerning the content or message of this manuscript. With respect to design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript, this study was funded in part by NIH grant

References (30)

  • M.I. Harris

    Diabetes in America: epidemiology and scope of the problem

    Diabetes Care

    (1998)
  • M.I. Harris et al.

    Prevalence of diabetes, impaired fasting glucose, and impaired glucose tolerance in U.S. adults. The Third National Health and Nutrition Examination Survey, 1988–1994

    Diabetes Care

    (1998)
  • S.P. Helmrich et al.

    Physical activity and reduced occurrence of non-insulin-dependent diabetes mellitus

    New England Journal of Medicine

    (1991)
  • M.M. Iversen et al.

    History of foot ulcer increases mortality among individuals with diabetes: ten-year follow-up of the Nord-Trondelag Health Study, Norway

    Diabetes Care

    (2009)
  • D.J. Margolis et al.

    Location, location, location: geographic clustering of lower-extremity amputation among Medicare beneficiaries with diabetes

    Diabetes Care

    (2011)
  • Cited by (0)

    Conflict of interest: The authors have no relevant conflicts of interest.

    View full text