How Accurate are Hospital Report Cards

A key statistic that consumer groups and the media often use when compiling hospital report cards and national rankings can be misleading, a Loyola study has found.

The statistic is called the mortality index. A number above 1.0 indicates a hospital had more deaths than expected within a given specialty. Lower than 1.0 means there were fewer than the expected number of deaths.

The study illustrates how the mortality index can be misleading in at least two major specialties -- neurology and neurosurgery. The index fails to take into account such factors as whether a hospital treats complex cases transferred from other hospitals or whether a hospital treats lower-risk elective cases or higher-risk non-elective cases.

"A hospital with a lower mortality index may not be a better hospital for patient care, but rather a place where the patient mix has been refined or limited," said Thomas Origitano, MD, chairman of the Department of Neurological Surgery, Loyola University Stritch School of Medicine.

There is no "definitive or reliable source for rating the quality of overall neurosurgical care," Origitano and colleagues wrote in the Journal of Neurosurgery.

Researchers cited several other problems with rating systems. For example, report cards typically lump neurology and neurosurgery into one category, neurosciences. This can be misleading if the neurology aspects of the rating system misrepresent the neurosurgical service or vice versa.

Another common practice is using reputation as one of the main ranking criteria. This practice "is at best subjective," Origitano said.