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. 1982 Dec;4(2):101-28.

Reliability and validity in hospital case-mix measurement

J Pettengill, J Vertrees

Reliability and validity in hospital case-mix measurement

J Pettengill et al. Health Care Financ Rev. 1982 Dec.

Abstract

There is widespread interest in the development of a measure of hospital output. This paper describes the problem of measuring the expected cost of the mix of inpatient cases treated in a hospital (hospital case-mix) and a general approach to its solution. The solution is based on a set of homogeneous groups of patients, defined by a patient classification system, and a set of estimated relative cost weights corresponding to the patient categories. This approach is applied to develop a summary measure of the expected relative costliness of the mix of Medicare patients treated in 5,576 participating hospitals. The Medicare case-mix index is evaluated by estimating a hospital average cost function. This provides a direct test of the hypothesis that the relationship between Medicare case-mix and Medicare cost per case is proportional. The cost function analysis also provides a means of simulating the effects of classification error on our estimate of this relationship. Our results indicate that this general approach to measuring hospital case-mix provides a valid and robust measure of the expected cost of a hospital's case-mix.

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Figures

Figure 1
Figure 1. Simulation Results Distribution of Percentage Error in the Case-Mix Index Values Due to Error in DRG Weights: 10 Percent Error
Figure 2
Figure 2. Simulation Results Distribution of Percentage Error in the Case-Mix Values Due to Errors in DRG Proportions: 10 Percent Error
Figure 3
Figure 3. Simulation Results Distribution of Percentage Error in the Case-Mix Index Values Due to Errors in Both Index Components: 10 Percent Error
Figure 4
Figure 4. Simulation Results Distribution of Percentage Error in the Case-Mix Index Values Due to Errors in Both Index Components: 30 Percent Error
Figure 5
Figure 5. Coefficient Change Due to Compression Effect of Additional Classification Error on Medicare Case-Mix
See this image and copyright information in PMC

References

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