Association Between Medicare Expenditure Growth and Mortality Rates in Patients With AMI

Health improvements for patients with acute myocardial infarction (AMI) varied across hospitals and were associated with the diffusion of cost-effective care, rather than overall expenditure growth between 1999 and 2014, according to a new study.

Identifying a lack of research on the association between long-term growth in Medicare spending and health outcomes, the authors of the study published in JAMA Cardiology assessed the relationship between growth in Medicaid expenditures and decreased mortality over the 15-year period.

“There is little agreement regarding the association between healthcare expenditures and outcomes, with estimates ranging from large and positive to 0 and negative,” wrote the authors. “Although it is well understood that not all spending is cost-effective, nearly all studies have summarized the multidimensional components of patient care by a single dollar measure—total expenditures—rather than considering how the money is spent.”

The authors examined a longitudinal patient-level database from the Medicare fee-for-service population of elderly patients admitted to the hospital for AMI between January 1, 1999, and January 30, 2014. A random 20% sample of Medicare beneficiaries for 1999, 2000, and 2004 and a 100% sample for 2008, 2013, and 2014 were assessed. The authors combined 2 years of data for January 1, 1999, through December 31, 2000, and January 1, 2013, through June 30, 2014, in order to increase statistical power in smaller hospitals.

The cohort of 479,893 patients included those:

• Enrolled in Medicare (Part A and Part B) for the entire year beyond index admission
• Aged at least 65 years at the time of their index admission
• Enrolled in a non—health maintenance organization plan for at least 1 month during each of the 12-month periods.

The 180-day, 30-day, and 31- to 180-day case fatality rates were assessed. Overall, 180-day case fatality rates declined from 26.9% in 1999-2000 to 21.5% in 2013-2014, with most of the decline due to the 30-day period. The 31- to 180-day fatality rate was not significantly changed between 1990-2000 and 2013-2014.

Overall inflation- and risk-adjusted 180-day mean expenditures per patient increased by 13% from 1999-2000 to 2013-2014; however, all of the increase had occurred by 2008. Total spending increased by 6.1% up to 30 days beyond the index admission and by 31% from 31 to 365 days beyond the index admission.

Mean expenditures in the 5.0% of hospitals (n  =  61) with the most rapid expenditure growth between 1999-2000 and 2013-2014 increased by 44.1% ($12,828 [SD = $2315]); for the 5.0% of hospitals with the slowest expenditure growth (n  =  61), mean expenditures decreased by 18.7% (−$7384 [$4141]; 95% CI, $8177-$6496).

Spending on cardiac procedures was positively associated with the 180-day mortality rate, whereas postacute care spending yielded moderate cost-effectiveness ($455,000 per life saved after 180 days; 95% CI, $323,000-$833,000).

“This moderation in spending observed for patients with AMI masks substantial and continued hospital variability with regard to growth or declines in overall spending, suggesting that local factors and not just national policy changes continue to be important components of expenditure growth,” concluded the authors.

Reference

Likosky DS, Van Parys J, Zhou W, Borden WB, Weinstein MC, Skinner JS. Association between Medicare expenditure growth and mortality rates in patients with acute myocardial infarction: a comparison from 1999 through 2014 [published online December 20, 2017]. JAMA Cardiol. doi: 10.1001/jamacardio.2017.4771.