Hospital mortality performance not boosted by readmission failure

By Caroline Price, Senior medwireNews Reporter

Researchers say they have found no evidence of a link between hospital performance as measured by 30-day mortality rates and that by 30-day readmission rates in US hospitals.

Harlan Krumholz (Yale University, New Haven, Connecticut) and team say their research should allay concerns that improved mortality rates are being achieved through higher-risk groups being discharged from hospital.

"Some researchers have raised concerns that hospital mortality rates and readmission rates might have an inverse relationship, such that hospitals with lower mortality rates are more likely to have higher readmission rates," the team explains, writing in JAMA.

However, the study of Medicare fee-for-service beneficiaries, aged 65 years or older, showed no association between mean 30-day risk-standardized mortality rates (RSMRs) and 30-day risk-standardized readmission rates (RSRRs) for either acute myocardial infarction (AMI) or pneumonia.

The analysis included data from the beginning of July 2005 to the end of June 2008 for AMI discharges at a total of 4506 hospitals, for heart failure discharges at 4767 hospitals, and for pneumonia discharges at 4811 hospitals.

The mean RSMRs and RSRRs were 16.60% and 19.94% for AMI, 11.17% and 24.56% for heart failure, and 11.64% and 18.22% for pneumonia, respectively.

Krumholz and team found no correlations between the RSMRs and RSRRs for AMI or pneumonia, either overall or by hospital subtype, including region, safety net status, and urban/rural status.

There was a significant inverse correlation between RSMRs and RSRRs for heart failure, but the authors explain that this was only modest and not seen throughout the entire range of performance. Although the association was again generally consistent across hospital subtypes, the authors note that the correlation was stronger for teaching, non-profit, and urban hospitals.

Further analysis dividing performance into quartiles of RSMRs and RSRRs showed a range of achievement across both measures - so there were both high and low performers on readmission across all mortality levels. Moreover, the authors note, "we show that hospitals can do well on both measures, with many hospitals having low RSMRs and RSRRs."

On the other hand, they emphasize that the lack of a significant positive association is also reassuring - as this could have inferred that the two measurements reflect similar processes and it is therefore not necessary to measure both.

Krumholz and team conclude: "From a policy perspective, the independence of the measures is important. A strong inverse relationship might have implied that institutions would need to choose which measure to address.

"Our findings indicate that many institutions do well on mortality and readmission and that performance on one does not dictate performance on the other."

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