Growth in medicare expenditures for patients with acute myocardial infarction: a comparison of 1998 through 1999 and 2008

Abstract

Importance: Medicare expenditures continue to grow rapidly, but the reasons are uncertain.

Objective: To compare expenditures from 1998 through 1999 and 2008 for Medicare beneficiaries hospitalized for acute myocardial infarction (AMI).

Design, setting, and participants: Cross-sectional analysis of a random 20% sample of fee-for-service Medicare beneficiaries admitted with AMI from 1998 through 1999 (n = 105,074) and a 100% sample for 2008 (n = 212,329).

Main outcomes and measures: Per-beneficiary expenditures, standardized for price and adjusted for risk and inflation. Expenditures were measured across 4 periods: overall (index admission to 1 year), index (within the index admission), early (postindex admission to 30 days), and late (31-365 days). RESULTS Compared with the subjects from 1998 through 1999, those in 2008 were older and had more comorbidities but slightly less ischemic heart disease and cerebrovascular disease. Although there was a 19.2% decline in the rate of hospitalizations for AMI, overall expenditures per patient increased by 16.5% (absolute difference, $6094). Of the total risk-adjusted increase in expenditures, 25.6% occurred within 30 days (22.0% attributed to the index admission), and 74.4% happened 31 to 365 days after the index admission. Spending per beneficiary within 30 days increased by $1560 (7.5%), and spending between 31 and 365 days increased by $4535 (28.0%). Expenditures for skilled nursing facilities, hospice, home health agency, durable medical equipment, and outpatient care nearly doubled 31 to 365 days after admission. Mortality within 1 year declined from 36.0% in 1998 through 1999 to 31.7% in 2008; of the decline, 3.3% was in the 30 days following admission, and 1.0% was in days 31 to 365.

Conclusions and relevance: Between 1998 and 2008, Medicare expenditures per patient with an AMI substantially increased, with about three-fourths of the increase in expenditures occurring 31 to 365 days after the date of hospital admission. Although current bundled payment models may contain expenditures within 30 days of an AMI, they do not contain spending beyond 30 days.

Figure 1. Expenditures for Rehospitalization, Based on Diagnostic-Related Group (for 1998-1999) and Medicare Severity–Diagnosis-Related Group (for 2008)

Expenditures reflect the total hospital facility cost (in 2008 US dollars) for the specific reason per patient with acute myocardial infarction (AMI) accrued during 1 year following index discharge.

Figure 2. Rehospitalization Rates Following Index Hospitalization per 100 Beneficiaries With Acute Myocardial Infarction (AMI) for 3 Common Conditions

Medicare did not reimburse cardiac defibrillator implants for coronary artery disease from 1998 through 1999; their use rates in this period are denoted with NA (not applicable).