A public response seems due for (the recent) letter from my friend Benita Kaimowitz expressing understandable concern about “U.S. News & World Report’s” score for the University of Michigan Hospitals in the category of patient safety.

I believe she has simply misread the magazine’s index, which actually appears to rank U-M at the best, rather than ‘lowest’ of five levels. I blame this misunderstanding entirely on the magazine, whose explanation of this index (“Max.=5”) is deficient and misleading.

Indeed, the introductory text to these rankings says that the patient safety index is weighted as five percent of the overall score given to each of the 50 best hospitals in each of 12 major adult care specialty areas, seemingly implying that a higher number is better. But the opposite must be the case, as indicated by comparison with Johns Hopkins and the Mayo Clinic, clearly the two top-rated hospitals across these specialties, which also receive “1” patient safety marks.


The format for these specialty tables is surely responsible further for Ms. Kaimowitz’s reading of this rating as “a pattern repeated in every major specialty …” This ranking actually covers all 12 specialties together, as the magazine should somehow have made explicit, so there is no issue of a repeated pattern; each hospital has the same safety rank in every table in which it appears (the Nurse Staffing and Nurse Magnet Hospital columns are potentially misleading in the same way).


I have no training in statistics. The magazine’s “Honor Roll” includes U-M at number 14, based upon “standard deviations above the mean” in each of the major 12 and four additional “especially difficult” specialty areas - this among 4,852 hospitals surveyed. Not bad; but I believe one can argue for an even better rating.

Among those hospitals that made “U.S. News’” top 50 in all the 12 major specialties, U-M’s average specialty score of 49.225 and its aggregate ranking (sum of 12 specialty rankings) of 186 are both ninth best. Furthermore, only two of these hospitals also appear on all four of the “especially difficult” specialty lists: Mayo Clinic and U-M. As a patient and a U-M alumnus, I think we can be justifiably proud of the U-M Hospitals.
 


Roger Wykes Ann Arbor