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Hospital Report CardsTM Methodology 5
May not be reprinted or reproduced without permission from Health Grades, Inc.
HealthGrades then took the above APR-DRG output and went through these steps:
1
For each patient, a predicted probability of death was calculated based on the average national
mortality rate for that mortality risk class in that APR-DRG.
2
Based on the observed and predicted deaths, a z-score was calculated for each hospital across the
APR-DRGs that defines the cohort.
3
Any hospital that did not have at least 30 cases across three years of data was removed, and any
hospital that did not have at least five cases in the most current year was removed.
Assignment of Star Ratings
The following rating system was applied to the data for all procedures and diagnoses:
Actual performance was better than predicted and the difference
was statistically significant.
Actual performance was not significantly different from what
was predicted.
Actual performance was worse than predicted and the difference
was statistically significant.
Limitations of the Data Models
It must be understood that while these models may be valuable in identifying hospitals that perform better
than others, one should not use this information alone to determine the quality of care provided at each
hospital. The models are limited by the following factors:
·
Cases may have been coded incorrectly or incompletely by the hospital.
·
The models can only account for risk factors that are coded into the billing dataif a particular risk
factor was not coded into the billing data, such as a patient's socioeconomic status and health
behavior, then it was not accounted for with these models.
·
Although Health Grades, Inc. has taken steps to carefully compile these data using its
methodology, no techniques are infallible, and therefore some information may be missing,
outdated or incorrect.
Please note that a high ranking for a particular hospital is not a recommendation or endorsement by Health
Grades, Inc. of a particular hospital; it means that the data associated with a particular hospital has met the
foregoing qualifications. Only individual patients can decide whether a particular hospital is suited for their
unique needs.
Also note that if more than one hospital reported to CMS under a single provider ID, HealthGrades analyzed
patient outcome data for those hospitals as a single unit. (Throughout this document, therefore, "hospital"
refers to one hospital or a group of hospitals reporting under a single provider ID.)
