Healthcare News & Insights

Mortality rates and readmission rates: Is there a link?

Any hospital executive on this earth wants his or her hospital to have lower mortality rates, and lower readmission rates. However, researchers are wondering if that is even possible. They’ve raised concerns that lower mortality rates actually may be linked to higher readmission rates. And that interventions that improve morality rates might increase readmission rates, and increase healthcare costs. So which scenario is correct?

It’s hard to say, but a recent study found that RSMRs and RSRRs weren’t associated in most cases.

While the Centers for Medicare & Medicaid Services (CMS) a  few years ago began publishing the hospital 30-day risk-standardized mortality rates (RSMRs) and risk-standardized readmission rates (RSRRs) for patients with acute myocardial infarction, heart failure and pneumonia, the evaluation of hospital performance as measured by RSMRs and RSRRs really hasn’t been delved into, until now.

Yet these measures have been proposed for use by CMS to punish hospitals with high readmission rates by reducing their payments. It’s estimated that in 2013, hospitals will lose about 0.3% of their funding, which adds up to $270 million overall.

So a group of researchers set out to find if there was a relationship between hospital readmission and mortality rates for patients hospitalized with acute myocardial infarction, heart failure or pneumonia. They recently published their findings in the Journal of the American Medical Association (JAMA).

New study

The study, which was led by Dr. Harlan Krumholz, of the Yale University School of Medicine, look at Medicare fee-for-service beneficiaries 65-years and older with a principal discharge diagnosis of acute myocardial infarction, heart failure or pneumonia, between July 1, 2005, and June 30, 2008.

It evaluated the association between RSMRs and RSRRs at 4,506 hospitals for acute myocardial infarction, 4,767 hospitals for heart failure and 4,811 hospitals for pneumonia.

The breakdown was:

  • acute myocardial infarction — 590,809 admissions for mortality and 586,027 readmissions
  • heart failure — 1,161,179 admissions for mortality and 1,430,030 readmissions, and
  • pneumonia — 1,225,366 admissions for mortality and 1,297,031 readmissions.


The mean RSMRs and RSRRs, respectively, were:

  • 16.60% and 19.94% for acute myocardial infarction
  • 11.17% and 24.56% for heart failure, and
  • 11.64% and 18.22% for pneumonia.

The correlations between RSMRs and RSRRs were:

  • 0.03 for acute myocardial infarction
  • −0.17 for heart failure, and
  • 0.002 for pneumonia.

What it all means

The researchers concluded that RSMRs and RSRRs weren’t associated for patients admitted with an acute myocardial infarction or pneumonia, and were only slightly associated, within a certain range, for patients admitted with heart failure.

They also found that between 5% and 9% of hospitals were able to have low readmission rates and low death rates, which should ease fears that doing well in one area means doing poorly in the other.

These findings also suggest mortality and readmission measures convey distinct information. The factors that are important with mortality, such as rapid triage and early intervention, are different from what’s important with readmission, like transition from inpatient to outpatient care, and patient education and support.

“Our findings show that many institutions do well on mortality and readmission, and that performance on one does not dictate performance on the other,” Dr. Krumholz, director of the Yale-New Haven Hospital Center for Outcomes Research and Evaluation, said in Yale News. “We found that hospitals can excel in both areas, dispelling prevalent concerns that hospitals that do well on mortality will necessarily do worse on readmission.”

“I think our goal should be to learn from the hospitals excelling in both areas and spread those ideas,” he added. “The measures are leading hospitals to invest in quality — and this study shows ideally they will be able to find ways to help people survive in the hospital and have a successful recovery — but that each area may require efforts that are specific to it.”

Dr. Krumholz also told the Yale Daily News that the belief that mortality and readmission rates are linked partly reflects growing concerns with the CMS’s readmissions penalty. “Some hospitals are saying you can’t really improve it, or it’s not their fault. So some people are grasping for things that are wrong with it.”

Study limitations

It’s important to note several limitations in the study.

According to the researchers, the first was that overall patterns were assessed. So it can’t be denied that in some hospitals, the performance of one measure influenced the performance of the other measure. Another limitation is that the hierarchical modeling can hide a relationship, since many hospitals have lower volume.

Finally, the study didn’t investigate the validity of the measures. However, the researchers pointed out:

  • the National Quality Forum, which has a rigorous vetting process, approved the measure to evaluate quality
  • CMS publicly reports them as quality measures, and
  • the Affordable Care Act incorporates them in incentive programs as quality measures.

Despite that, the study was designed to determine the link between mortality and readmission rates, not to evaluate the validity of the measures.

The next step, according to researchers, is that these CMS measures need to be examined across the different types of hospitals, because they change. For example, large teaching hospitals tend to have higher readmission rates. The key challenge is going to be identifying the factors behind the low readmissions rates of some teaching hospitals.

“We’re trying to solve the problem, not just understand the metrics,” Dr. Krumholz said. “Our real drive is to make the health care system more effective.”

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