Korean J Prev Med.  2001 Aug;34(3):244-252.

Severity Measurement Methods and Comparing Hospital Death Rates for Coronary Artery Bypass Graft Surgery

• Kwon Y
• Ahn H
• Shin Y

Abstract

OBJECTIVE
Health insurers and policy makers are increasingly examining the hospital mortality rate as an indicator of hospital quality and performance. To be meaningful, a risk-adjustment of the death rates must be implemented. This study reviewed 5 severity measurement methods and applied them to the same data set to determine whether judgments regarding the severity-adjusted hospital mortality rates were sensitive to the specific severity measure.
METHODS
The medical records of 584 patients who underwent coronary artery bypass graft surgery in 6 general hospitals during 1996 and 1997 were reviewed by trained nurses. The MedisGroups, Disease Staging, Computerized Severity Index, APACHElll and KDRG were used to quantify severity of the patients. The predictive probability of death was calculated for each patient in the sample from a multivariate logistic regression model including the severity score, age and sex to evaluate the hospitals' performance, the ratio of the observed number of deaths to the expected number for each hospital was calculated.
RESULTS
The overall in-hospital mortality rate was 7.0%, ranging from 2.7% to 15.7% depending on the particular hospital. After the severity adjustment, the mortality rates for each hospital showed little difference according to the severity measure. The 5 severity measurement methods varied in their statistical performance. All had a higher c statistic and R2 than the model containing only age and sex. There was a little difference in the relative hospital performance evaluation by the severity measure.
CONCLUSION
These results suggest that judgments regarding a hospital's performance based on severity adjusted mortality can be sensitive to the severity measurement method. Although the 5 severity measures regarding hospital performance concurred, more often than would be expected by chance, the assessment of an individual hospital mortality rates varied by the different severity measurement method used.

Keyword

Severity of illness index; Risk adjustment; Coronary artery bypass grafting; Inhospital mortality

MeSH Terms

Administrative Personnel
Coronary Artery Bypass*
Coronary Vessels*
Dataset
Hospital Mortality
Hospitals, General
Humans
Insurance Carriers
Judgment
Logistic Models
Medical Records
Mortality*
Risk Adjustment
Severity of Illness Index
Transplants