Thirty-Day Readmission in Acute MI Not Linked With Hospital Care or Clinical Outcomes

The 30-day readmission rate for centers treating patients with acute myocardial infarction is not associated with either the quality of care during the index hospitalization or clinical outcomes after discharge, according to the results of a new study.

Notably, hospitals with higher 30-day readmission rates treated a higher proportion of black patients, a finding that suggests these hospitals are treating more “socioeconomically vulnerable patient populations” and are more likely to be penalized for higher readmission rates. Hospitals with more readmissions also tended to treat patients with more prevalent heart failure symptoms, lower ejection fractions, and more bleeding events.

“I think the metric is a good metric in terms of the financial incentives,” lead investigator Ambarish Pandey, MD (University of Texas Southwestern Medical Center, Dallas), told TCTMD. “Studies have shown that the implementation of readmission penalties results in a decline in the readmission rates. Hospitals are benefiting by reducing the costs of care, because readmission is a huge driver of cost. However, it might not be the ideal metric for improving long-term clinical outcomes or quality of care provided in-house. There need to be some changes in terms of how these metrics are assessed.”

For example, Pandey said the risk-standardized 30-day readmission rate should be adjusted for the socioeconomic distribution of the patient population at hospitals and the disease severity in the patient-case mix, so that inequities observed in their study are taken into account.

The results of the study were published April 26, 2017, in JAMA Cardiology.

HRRP Performance Metric

The Centers for Medicare & Medicaid Services implemented the Hospital Readmission Reduction Program (HRRP) in 2012 to provide financial incentives for hospitals to reduce readmission rates. In 2013, the maximum penalty was 1% of Medicare base payments for hospitals with higher-than-expected risk-standardized 30-day readmission rates for heart failure, MI, and pneumonia.

To TCTMD, Pandey said they conducted a similar study in heart failure patients. Published in 2016, the study observed comparable quality of care and clinical outcomes among 171 centers with high- and low-risk adjusted 30-day heart-failure readmission rates. Those findings, concluded the researchers, raised questions about the validity of the HRRP performance metric for identifying and penalizing underperforming hospitals.

In the present study, Pandey and colleagues attempted to address a similar question, that being whether the 30-day readmission rate was associated with quality of care and clinical outcomes in MI patients. In-hospital quality of care included adherence to such measures as prescribing aspirin at arrival, evaluation of ejection fraction, and reperfusion therapy and PCI within 90 minutes for STEMI patients, as well as discharge metrics such as prescribing optimal medical therapy, providing advice for quitting smoking, and referral to cardiac rehabilitation.

Using data from the National Cardiovascular Data Registry/Acute Coronary Treatment and Intervention Outcomes Network Registry-Get With the Guidelines (NCDR ACTION Registry-GWTG) sites participating in the first cycle of the HRRP, the analysis included data on 176,644 patients presenting within acute MI at 380 hospitals.

Overall, there was no significant association between adherence to MI performance measures and the 30-day readmission rates. There was a higher risk of 1-year mortality/all-cause hospital readmission among patients treated at centers with higher readmission rates, but this risk was driven by an increase in rehospitalizations within the first 30 days. In a landmark analysis beginning 30 days after discharge, there was no association between higher hospital readmission rates and clinical outcomes. 

“We also saw there was inequitable distribution of penalties among the hospitals, such that hospitals that were treating a greater proportion of socially or medically disadvantaged patients are unfairly penalized despite providing comparable quality of care and similar long-term clinical outcomes,” Pandey.  

‘Misunderstanding’ the Metric

Harlan Krumholz, MD (Yale University School of Medicine, New Haven, CT), who led the research underlying the risk-adjustment model for the HRRP, said the study “misunderstands” the 30-day readmission measure.

“[It was] not designed to reflect in-hospital processes, which have largely topped out due to the marked increase in quality over the past 15 years, or mortality, which is predicted by different features than readmission and has different causal factors,” he told TCTMD by email. “Best we can tell, readmission has to do with largely unmeasured hospital events, including patient preparation for discharge, transitional care, coordination/collaboration among providers, communication among patients and their clinicians, and other [factors], perhaps including the degree to which errors or poor nutrition or inactivity or poor rest occurred during the hospitalization.”

As a result, he would not expect the 30-day readmission rate to correlate with in-hospital process measures, which were introduced two decades ago, or with mortality. The present study, he added, does not suggest the 30-day readmission metric is invalid or not useful given the lack of correlation, but rather the opposite: that it is needed to capture all the unmeasured actions that current metrics miss.

“For patients, an unnecessary trip back to the hospital—a trip that could be prevented—is unwelcome,” said Krumholz. “Progress in reducing readmission rates without evidence of any harm is good news for them.”

Pandey made a similar argument, noting that readmission after an initial hospitalization for MI is not necessarily related to the care provided at the hospital. “It is largely driven by what happens once the patient is discharged,” he said. For example, how good is their follow-up, do they take their medication, and do they have social and economic support as well as technological support? Given that these factors are not related to in-hospital care, “it might be the reason we’re not seeing an association,” Pandey suggested.

Regarding long-term clinical outcomes, Pandey added that the disease process, as well as the severity of disease, is the largest influencer rather than rehospitalization.

“While the 30-day readmission rate is regarded as a bad thing, in some cases, patients who are sicker will definitely come in more often and they may get more care because they’re coming in,” he said. “Paradoxically, that might make long-term outcomes better than in centers with lower readmission rates at 30 days. It’s a phenomenon that has been seen in heart failure patients, particularly in our previous study.”