In our nationally representative sample of Medicare beneficiaries with heart failure near the end of life, comorbid diabetes was present in 42% of decedents. This prevalence was similar to findings from a number of other contemporary studies of heart failure patients, in which diabetes prevalence has ranged from 20 to 45%. [3
] The presence of diabetes was associated with increased expenditures in Medicare during the last six months of life, primarily related to increases in hospitalizations and inpatient expenditures. We found diabetes to be associated with some, but not all, cardiovascular procedures, while beneficiaries with diabetes had higher rates of intensive care unit stays than beneficiaries without diabetes. Conversely, diabetes was associated with reduced hospice use.
We found that Medicare expenditures for beneficiaries with diabetes were on average $10,000 higher than those for their counterparts without diabetes in the last six months of life. Following adjustment for covariates, diabetes was associated with an 8% increase in total expenditures. This associated increase in expenditures was similar to results from a prior study of heart failure patients at a single hospital center, although the prior findings were aggregated over a two-year period and did not specifically evaluate end-of-life expenditures. [7
] Similarly, other studies have found diabetes to be associated with increased expenditures following incident heart failure although have not examined the high cost period near the end of life. [2
] In a general Medicare population, diabetes was recently shown to be associated with a 16% increase in expenditures near the end of life. [15
] We found diabetes to be associated with increased expenditures among a cohort of individuals with heart failure, a chronic disease known to be associated with high costs, particularly near the end of life. [16
In our study, diabetes was associated with increased hospitalization rates and days spent in the hospital. Previous studies have shown diabetes in heart failure to be associated with poor outcomes, including increased rates of hospitalizations and increased hospital length of stay. [6
] Nonetheless, comorbid diabetes has not consistently predicted hospitalization-related costs in adults with heart failure. [14
] We found that diabetes was associated with increased inpatient related expenditures in a cohort of Medicare decedents with heart failure. Furthermore, costs related to hospitalizations appeared to be the primary driver of increased total expenditures observed among beneficiaries with diabetes as compared to those without diabetes.
Our findings suggest that strategies to keep individuals with heart failure and diabetes out of the hospital may be a promising approach to reduce costs. Clinical trials have shown medical interventions including beta-blocker therapy and blockade of the renin angiotensin aldosterone system to be efficacious at reducing hospitalizations among individuals with both heart failure and diabetes. [19
] From a health delivery standpoint, close physician follow-up may be associated with lower rates of hospitalization among individuals with heart failure near the end of life. [21
] Outpatient disease management programs have been shown to reduce hospitalizations in heart failure. [22
] In particular, we found that certain demographic and clinical characteristics were associated with increased expenditures among Medicare beneficiaries with diabetes and heart failure. These characteristics, which included reduced age, race other than white, increased number of prior hospitalizations, and certain comorbidities, may be useful to help identify which patients may most benefit from intensive multi-disease management.
Our study focused on individuals near the end of life, a population for whom hospice care has been shown to reduce hospitalizations [23
] and may reduce total expenditures, [24
] although this has not been consistently shown. [25
] While Medicare data does not include end of life preferences, more than one-third of beneficiaries in our study had chosen to enroll in hospice care, a notable finding given the older age and high rate of comorbidity of beneficiaries in this study. However, decedents with comorbid diabetes had lower rates of hospice use than their counterparts free of diabetes. Given the high rates of hospitalizations observed among beneficiaries with diabetes and heart failure coupled with the potential economic and non-economic benefits of palliative care, improvement in end of life discussions in this population might help reduce expenditures.
Diabetes was associated with increased prevalence of comorbidities other than dementia. Among beneficiaries with diabetes, most comorbidities were associated with increased costs. Therefore, the association between diabetes and increased utilization may have been partially mediated by other conditions. Nonetheless, after adjustment for these covariates, diabetes was still associated with increased expenditures and hospitalizations.
Our study has several limitations. First, our use of diagnostic coding may have led to errors in misclassification, although we used a validated algorithm to define both heart failure [26
] and diabetes. [27
] Our reliance on claims data limited our ability to identify certain clinical factors that may have affected outcomes in our study, including markers of disease severity such as functional status, glycosylated hemoglobin, and ejection fraction. As a result of lack of data on ejection fraction, we were unable to characterize beneficiaries as having heart failure with preserved versus reduced ejection fraction. This distinction may have led to additional confounding. Nonetheless, some studies have found diabetes to be similarly prevalent in heart failure with preserved and reduced ejection fraction, [28
] so the difference in heart failure classification between beneficiaries with and without diabetes may have been small. The claims data did not allow us to fully evaluate differences in treatment uptake between beneficiaries with and without diabetes. In particular, we could not determine frequency of enrollment in disease management programs nor adherence to heart failure medications, both of which have been shown to be efficacious in heart failure patients. Claims were also limited to direct Medicare costs and thus our results do not reflect data on both direct and indirect costs to patients and their families. We did not have available patient reported outcomes or patient preferences, which are particularly important in end-of-life care. This study specifically addressed resource utilization near the end of life, a period often characterized by high intensity of care. Our findings of an association between diabetes and utilization may not be generalizable to beneficiaries with heart failure who are not in the last six months of life.
In conclusion, diabetes is common in heart failure near the end of life and associated with increased expenditures, hospitalizations, and other markers of utilization. Comorbid diabetes should be specifically considered in programs aimed at improving care and reducing unnecessary hospitalizations and costs for patients with heart failure.