According to a recent cost study of year 2010 Medicare patients:

• High-cost patients (those in the top 10% of Medicare spending) accounted for 79% of inpatient costs, 9.6% of which were due to preventable hospitalizations
• In contrast, 16.8% of non-high-cost patients' inpatient costs were due to preventable hospitalizations
• High-cost patients accounted for 32.9% of total Emergency Department (ED) costs
• 41% of high-cost patients' ED costs were potentially preventable compared with 42.6% of ED costs for non-high-cost patients

Source: "Contribution of Preventable Acute Care Spending to Total Spending for High-Cost Medicare Patients," The Journal of the American Medical Association, abstract only, June 24, 2013, http://jama.jamanetwork.com/article.aspx?articleid=1699911