MORTALITY AND LENGTH OF STAY AS PERFORMANCE INDICATORS FOR PNEUMONIA IN THE ELDERLY

Background: Mortality and length of stay are frequently used as perfor mance measures for hospitals, If they are valid measures, they should be reproducible from year to year with attributable variation rather t han random variation. Methods: We compared hospitals on 2 outcomes, mo rtality and length of stay, in pneumonia in Medicare patients, The dat abase was from 20 Illinois hospitals with the largest number of discha rges for diagnosis-related group 89 (pneumonia with complications/como rbidities) for the years 1989 through 1992, This comprised 16,249 clai ms for hospitalization in patients 65 years of age or older. Results: The distributions showed trends toward lower mortality and shorter sta ys over the 4 years, Correlation of performance from year to year at e ach hospital for mortality was low with none of the calculated correla tion coefficients significant at p < .05, Correlations for length of s tay were higher (all coefficients significant at p < .01), For length of stay, the correlation between 1991 and 1992 was .766 (p < .00005, r (2) = .587), showing that nearly 60% of differences (variance) were ca used by differences in performance, In contrast, for mortality in 1991 and 1992, the correlation was .301 (p = .0986, r(2) = .091), showing that less than 10% of differences (variance) between hospitals were ca used by differences in performance, Similar results were obtained when the 20 hospitals were ranked and their rank correlations calculated. Conclusion: For pneumonia in Medicare patients, differences in length of stay between hospitals are caused by differences in performance, wh ile differences in mortality are random.