In-Hospital, 30-Day Standardized Mortality Measures Differ

In-hospital risk-standardized mortality rates vary between hospitals; linked with length of stay

THURSDAY, Jan. 5 (HealthDay News) -- The mean risk-standardized mortality rates (RSMRs) differ for in-hospital and 30-day models, with wide variability across U.S. hospitals, according to a study published in the Jan. 3 issue of the Annals of Internal Medicine.

Elizabeth E. Drye, M.D., from the Yale-New Haven Hospital Center for Outcomes Research and Evaluation in Connecticut, and colleagues investigated the agreement between in-hospital RSMRs and 30-day RSMRs as a means of assessing hospital performance. Patients admitted to nonfederal acute care U.S. hospitals, with at least 30 admissions for acute myocardial infarction (AMI), heart failure, and pneumonia, from 2004 to 2006, were enrolled. Participants included 718,508 admissions to 3,135 hospitals for AMI, 1,315,845 admissions to 4,209 hospitals for heart failure, and 1,415,237 admissions to 4,498 hospitals for pneumonia.

The investigators found that, for each condition, the mean hospital-level patient length of stay (LOS) varied across hospitals, from 2.3 to 13.7 days for AMI, 3.5 to 11.9 days for heart failure, and 3.8 to 14.8 days for pneumonia. The mean RSMR differences (30-day RSMR minus in-hospital RSMR) for AMI, heart failure, and pneumonia were 5.3, 6.0, and 5.7 percent, respectively, with across-hospital distribution varying widely. A difference in the performance classifications between the in-hospital and 30-day models was seen for 8.2, 10.8, and 14.7 percent of hospitals for AMI, heart failure, and pneumonia, respectively. For all three conditions, there was a positive association between hospital mean LOS and in-hospital RSMRs.

"In-hospital mortality measures provide a different assessment of hospital performance than 30-day mortality and are biased in favor of hospitals with shorter LOSs," the authors write.

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