CMS metric for 30-day readmissions may not be linked with improved care quality, outcomes after MI

Overall adherence to acute process-of-care measures for myocardial infarction (MI) was high and did not differ significantly by whether hospitals had more or fewer admissions.

Excess readmission ratio (ERR), the performance measure used by CMS as part of its Hospital Readmissions Reduction Program, is not associated with improved care quality or long-term clinical outcomes after acute myocardial infarction (MI), a recent study suggested.

To examine the association between MI-ERR and inpatient care quality, researchers used data from consecutive patients admitted with MI (n=229,252) to 519 hospitals from July 1, 2008, to June 30, 2011 (the time period used to calculate readmission penalties for the first cycle of the CMS program). Process-of-care outcomes included adherence to MI performance measures (acute and discharge), as well as a composite defect-free care metric.

To examine readmissions and mortality, researchers performed a one-year outcome analysis in 51,453 patients from 377 sites who were discharged alive from the index hospitalization and had follow-up data available. Clinical outcomes included days from discharge to the composite of all-cause mortality and all-cause readmission within one year of discharge.

Results were published online on April 26 by JAMA Cardiology.

Researchers grouped hospitals into four categories based on their ERR for MI for fiscal year 2013 (one group with MI-ERR≤1 and three groups with MI-ERR>1). There were minimal differences in age and proportion of women across groups, but the proportion of black patients was significantly higher among groups with MI-ERR greater than 1 than the group with MI-ERR of 1 or less (7.6% vs. 4.5%; P=0.01).

Overall adherence to MI process-of-care measures was high, and researchers found no significant differences between groups in the unadjusted adherence to acute MI measures. Centers with higher MI-ERR showed a significantly yet modestly lower rate of use of aspirin and beta-blockers at discharge (P=0.03 and P=0.04, respectively) than those with lower MI-ERR. Defect-free care was not significantly associated with continuous measures of MI-ERR in unadjusted or adjusted analyses.

For long-term outcomes, the overall adjusted analysis (1 to 365 days after discharge) showed that the risk for the composite outcome of mortality or all-cause readmission within one year was higher with increasing MI-ERR (9% higher risk per 0.1-unit increase in MI-ERR up to 1; 6% higher risk per 0.1-unit increase thereafter). However, in the adjusted landmark analysis (31 to 365 days after discharge), MI-ERR was not significantly associated with long-term risk for composite outcomes.

The study authors noted limitations to their work, such as how hospitals were National Cardiovascular Data Registry/Acute Coronary Treatment and Intervention Outcomes Network Registry–Get With the Guidelines centers that participated in the first cycle of the Readmissions Reduction Program, so results may not be generalizable to all hospitals. They added that they did not consider ED visits or observation status admissions during follow-up and that the results may not be applicable to the time period after the study (2012 and later).

They emphasized that the number of black patients and those with higher clinical severity (e.g., more prevalent heart failure symptoms, lower ejection fraction, more bleeding events) were significantly higher at centers with higher MI-ERR. They added that the CMS measure adjusts for many hospital-level differences in patient characteristics (e.g., age, comorbidities, patient case-mix) but does not account for race/ethnicity or any measures of symptoms or ejection fraction.

“Because MI-ERR does not associate with indices of quality of care or 1-year mortality or readmissions between 31 and 365 days, our findings raise questions of whether CMS readmissions penalties are equitably and justly applied for hospitals with a high prevalence of socially and/or medically complex patients,” they wrote.