A study in the New England Journal of Medicine has found wide disparities among four common measures of hospital-wide mortality rates, which compare a hospital's actual patient death rate to statistical predictions.
The study compared four measures of hospital-wide mortality provided by commercial vendors. Each vendor received identical discharge data from Massachusetts acute care hospitals from October 1, 2004, through September 30, 2007 and used the data to calculate each hospital's mortality rate.
The researchers found that the four common methods for calculating hospital-wide mortality produced substantially different results, which included both higher- and lower-than-expected rates for the same Massachusetts hospitals during the same year. The researchers conclude that the variation may have resulted from a lack of standardized national eligibility and exclusion criteria, different statistical methods, or fundamental flaws in the hypothesized association between hospital-wide mortality and quality of care.