Quality in 30-day post-MI mortality linked to increased life expectancy

1. Hospitals and provider organizations are increasingly compared and benchmarked based on short-term outcome measures, such as the risk-adjusted 30-day mortality rate following acute myocardial infarction (AMI).

2. On average, patients treated at high-performing hospitals in terms of 30-day AMI mortality were more likely to have extended life expectancy and improved long-term outcomes compared to those treated at low-performing institutions.

Evidence Rating Level: 2 (Good)

Study Rundown: With the Affordable Care Act, hospitals are increasingly compared based on a number of metrics, including 30-day mortality rates after AMI. In this study, the authors investigated whether differential 30-day mortality rates for AMI were associated with differences in long-term outcome, therefore validating the use of these short-term quality metrics. Drawing on 17 years of follow-up data from a Medicare database, it was found that on average, patients treated at high-performing hospitals lived longer. These results lend credence to the notion that investments to improve short-term hospital performance may yield benefits over the longer term. This is in contrast to previous work that has shown that investments in process measures that have not necessary improved variation in mortality relates related to AMI. However, these data are observational in nature (for which the authors adjusted for a number of known confounders), but residual confounding associating better life expectancy with “high performer” hospitals remains possible, as does the fact that improvements in the standard of care in AMI since these data were collected in the 1990s may limit the study’s generalizability.

Click to read the study, published in NEJM

Relevant Reading: The inverse relationship between mortality rates and performance measures in the Hospital Quality Alliance Measures

In-Depth [retrospective cohort]: Data were collected from the Cooperative Cardiovascular Project, involving Medicare patients hospitalized with AMI between 1994 and 1996 and had 17 years of follow-up. This included a total of 119 735 patients across 1824 hospitals. There were a number of exclusion criteria including age less than 65 years, unconfirmed AMI by chart review, repeat hospitalization, or admission from ambulatory surgery or other hospital stays. 1824 hospitals were stratified into quintiles based on expected mortality, a marker of case mix or patient risk. Again, within these strata, hospitals were stratified into quintiles based on risk-standardized mortality rates, and models were performed for each case-mix stratum to compare life expectancies. With each case-mix stratum, patients in the lowest risk standardized mortality rate quintile had the highest probability of survival, a finding that was consistent across time.

After adjustment for a number of clinical and treatment related variables, patients treated at high-performance hospitals lived on average 1.14 years (95%CI 0.84 to 1.44) longer than those in low performance hospitals in the lowest case-mix stratum, and 0.84 years longer on average in the highest case-mix stratum (95%CI 0.60 to 1.09). Differences in life expectancy across risk-standardized mortality rate quintiles were significant across all 5 case-mix strata (p < 0.001 for all comparisons). When 30-day AMI survivors were examined separately, survival curves for patients in all risk-standardized quintiles were the same in each of the five case-mix strata arguing against the possibility that hospitals with lower 30-day risk-standardized mortality rate had merely forestalled death within 30 days.

Image: PD

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