JAMA: Researchers observed a 19.2% drop in AMI hospitalizations, but 16.5% increase in expenses
"The researchers observed a 19.2% decrease in the rate of AMI hospitalizations, but overall per-patient expenditures increased by 16.5%. About one-quarter (25.6%) of the total risk-adjusted increase in expenditures occurred within 30 days, and 74.4% occurred 31–365 days after the index admission. There were increases in spending per beneficiary within 30 days (7.5% increase; $1,560) and between 31 and 365 days (28% increase; $4,535). From 31–365 days after admission, the expenditures for skilled nursing facilities, hospice, home health agencies, durable medical equipment, and outpatient care almost doubled."
Medicare expenditures continue to grow rapidly, but the reasons are uncertain.
To compare expenditures from 1998 through 1999 and 2008 for Medicare beneficiaries hospitalized for acute myocardial infarction (AMI).
Design, Setting, and ParticipantsCross-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).
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 RelevanceBetween 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.
Between 2000 and 2010, the growth in Medicare expenditures per enrollee, without adjusting for inflation, was about 5.9% annually, considerably greater than the 2.8% annual growth in gross domestic product.1- 2 Given the large budget deficits in the United States and the high cost of caring for Medicare beneficiaries, unanswered questions remain: why have Medicare costs been rising so rapidly? Do reimbursement rates, or the mix of services per disease, account for increased expenditures? Alternatively, has the threshold for treatment decreased so that patients are treated more aggressively?
We addressed these questions with detailed Medicare claims data and focused on a well-defined index event: hospital admission for acute myocardial infarction (AMI). Patients with AMI are almost universally hospitalized (making this a reliable index event). The considerable technological progress in the treatment of AMI has improved survival rates.3 For the index admission, our hypothesis was that changes in both the technology of treatment and reimbursement rates led to increased costs. For the acute (within 30 days of the AMI) and longer-term (31-365 days) postadmission periods, our hypothesis was that treatment intensity increased for patients after their initial hospitalization.
We used a random 20% sample of Medicare beneficiaries from 1998 through 1999 and a 100% sample for 2008. Eligible patients were fee-for-service Medicare enrollees with the diagnosis of AMI based on the presence of appropriate diagnosis codes from the International Classification of Diseases, Ninth Revision (410.xx [except 410.x2]), from 1998 through 1999 or 2008. Eligibility in the sample was limited to those (1) enrolled in Medicare (Part A and B, as identified through the Medicare denominator file) for the entire year beyond their index admission (or until the month of their death), (2) at least 65 years or older at the time of their index admission, and (3) enrolled in a non–health maintenance organization plan for more than 1 month during each of the 12-month periods (eFigure in the Supplement). Data from the Medicare Provider Analysis and Review files were linked to other Centers for Medicare & Medicaid Services files (Carrier file, Home Health Agency, Durable Medical Equipment, Outpatient, and Hospice) containing claims that represented services associated with the patient’s index admission and subsequent services (and expenditures) for a 1-year period following admission. Outpatient claims differ from physician claims; they include bills from rehabilitation facilities, hospital outpatient departments, and other institutional outpatient providers.
We excluded patients admitted to a non–acute care hospital with a primary diagnosis of AMI, those transferred to an acute care hospital with a primary diagnosis other than AMI, and those discharged alive with a total length of stay less than 1 day and who were not transferred. These exclusions left a total of 317 403 patients in our final sample (eFigure in the Supplement).
We defined a transfer as occurring if the date of discharge was the same as the date of admission between 2 mutually exclusive hospitals. The total length of stay for the index admission was defined from the date of admission to discharge, including any transfers.
Calculation of Expenditures
We report price-standardized Medicare payments for the index admission and postindex use up to 1 year following a patient’s hospitalization for AMI.4 Standardized Medicare payments adjust for differences across regions in reimbursement rates for Medicare services owing to costs of living, graduate medical education, and payments provided for serving a disproportionate number of low-income patients.
Hospital payments included the acute index hospitalization (diagnostic-related group [DRG] payment plus outlier payments when present) and other hospitalizations occurring within 1 year of the initial admission date. Expenditures included actual payments to providers but not amounts billed to patients or their supplemental insurance policies.
We disaggregated expenditures after the index admission into the specific categories of hospital use and accounted for changes in definitions of DRGs over time, including the (new) Medicare Severity–Diagnosis-Related Group (MS-DRG) categories (eTables 1 and 2 in the Supplement). Because of the difficulty of risk-adjusting each specific DRG/MS-DRG category in every period, we present unadjusted expenditures.
Physician Payments and Use
We provide use of and payments for physician services based on current procedural terminology and the Berenson-Eggers type of service codes.5 The Berenson-Eggers codes create clinically relevant service categories for analyzing Medicare expenditures.
Other Expenditures After the Index Hospitalization
We included expenditures for skilled nursing facilities, outpatient facilities, home health agency, hospice, and durable medical equipment.
We calculated the population-based rates of AMI hospitalizations and total expenditures (index and postindex admission) for all fee-for-service Medicare beneficiaries. The 1998 through 1999 expenditures are expressed in terms of 2008 US dollars after adjustment for general inflation using the chain-weighted gross domestic product price deflator. We adjusted for age, sex, race, ST-segment AMI, and Charlson comorbidities (including 13 comorbid conditions previously predictive of long-term mortality).6 We used 2-sample t tests (for unequal sample sizes and unequal variances across periods). Although our study was not designed to test the causal effect of greater spending levels on health outcomes, we used a similar risk adjustment approach to compare 30-day rates from 1998 through 1999 with corresponding 31- to 365-day case fatality rates in 2008.
We identified 317 403 Medicare beneficiaries who were hospitalized for an AMI (105 074 from the 20% sample of enrollees in 1998-1999 and 212 329 from the 100% sample in 2008). These comprised 0.64% of all fee-for-service Medicare enrollees from 1998 through 1999 and 0.47% in 2008 (P < .001). Thus, there was a 19.2% decline in the incidence of AMI during the decade.
As shown in Table 1, patients in 2008 were older and sicker on average than patients in 1998 through 1999 and had more comorbid conditions, exclusive of less ischemic heart disease and cerebrovascular disease (all P < .001). There was a shift from coronary artery bypass graft (CABG) surgery during the index admission to percutaneous coronary intervention. Median length of stay was 1 day shorter in 2008 (5 vs 6 days in 1998-1999, P < .001). Reductions in length of stay were associated with concomitant increases in other expenditures, including a 75.4% increase in the use of skilled nursing facilities in the first 30 days (Table 2).
Overall, 1-year case fatality rates per patient with AMI declined from 36.0% from 1998 through 1999 to 31.7% in 2008; of the 4.3% decline, 3.3% was in the 30 days following admission (from 18.6% to 15.3%) and 1.0% was in days 31 to 365. The case fatality rate for days 31 to 365 (among patients surviving for 30 days after an AMI) declined from 22.3% to 20.2%. The available data did not allow us to measure changes in quality of life.
Adjusted 1-year expenditures increased 16.5% (absolute difference, $6094) for 1998 through 1999 compared with 2008 (Table 2). Spending per beneficiary within 30 days increased by $1560 (7.5%), and spending between 31 and 365 days increased by $4535 (28.0%). Medicare expenditures in the first 30 days accounted for 25.6% of the increase in spending (22.0% attributed to the index admission); expenditures between 31 and 365 days after admission accounted for the remaining 74.4%. The components of the 74.4% increase between 31 and 365 days were home health agency, hospice, or durable medical equipment (22.9%); skilled nursing facilities (17.3%); inpatient (12.8%) and outpatient (11.1%) services; and physician payment (10.4%).
Table 2. Total, Index, and Postindex Admission Spending for Patients Admitted for Acute Myocardial Infarctiona
Together, inpatient and skilled nursing facility spending accounted for the greatest absolute change in cost (total of $3033) during 1 year (Table 2) and the greatest proportion of the overall cost increase (48.8%). Growth in home health agency and hospice expenditures was not associated with declines in inpatient facility expenditures.
From 1998 through 1999, 33.9% of the cohort was rehospitalized within 3 months of the index admission (20.0% within 1 month) compared with 33.4% within 3 months in 2008 (19.8% within 1 month). Although overall rates of readmission did not change appreciably, the mean cost per readmission increased by 9.8% ($8991 in 1998-1999 to $9874 in 2008).
The greatest absolute increases (from 1998-1999 to 2008) in hospital facility expenditures during 1 year per patient with AMI were for percutaneous coronary intervention ($571) and cardiac defibrillator implantation ($541), the latter a technology not reimbursed by Medicare for coronary artery disease from 1998 through 1999 (Figure 1). Unadjusted expenditures for cardiac defibrillator implantation, rehabilitation, or septicemia accounted for 47.1% of the increase in hospitalization costs after the index admission.
Physician expenditures per beneficiary decreased by 1.0% during the index admission and were unchanged within the first 30 days (Table 2). Between 31 and 365 days, physician expenditures increased by $632 (21.8%), primarily because of a 43.5% increase in outpatient physician spending (Table 2). The greatest per-beneficiary increase in expenditures after the index admission, $498, was for durable medical equipment or “other services or exceptions,” such as ambulance transport and chiropractic care (Table 3). Expenditures in this category increased from $602 in 1998 through 1999 to $1100 in 2008.
Table 3. Rates and Expenditures for Physician and Other Servicesa in 1998 Through 1999 and 2008 After the Index Admission for Acute Myocardial Infarction (AMI)b
Physician expenditures for cardiac procedures after the index hospitalization declined from $1120 per patient from 1998 through 1999 to $803 in 2008, or by 28.3% (Table 3). The rate of rehospitalizations for percutaneous coronary interventions increased from 1.7 per 100 patients with AMI from 1998 through 1999 to 5.4 in 2008 (Figure 2). However, the rehospitalization rate for CABG surgery declined from 3.1 per 100 patients with AMI from 1998 through 1999 to 1.4 in 2008, or by 54.8%. Medicare’s cost per patient during 1 year for those undergoing inpatient percutaneous coronary interventions, with adjustment for inflation but not risk, was $12 327 from 1998 through 1999 and $14 385 in 2008, a 16.7% increase. Medicare’s cost per patient during 1 year for rehospitalizations in which a CABG was performed, with adjustment for inflation but not risk, was $31 727 from 1998 through 1999 and $30 686 in 2008. For both percutaneous coronary interventions and the rehospitalizations for CABG, the figures for cost per patient include the instances when a patient had more than 1 percutaneous coronary intervention or more than 1 rehospitalization for CABG within the year; the figures are not per percutaneous coronary intervention or per rehospitalization for CABG.