INFLUENCE OF EJECTION FRACTION ON HOSPITAL MORTALITY, MORBIDITY, AND COSTS FOR CABG PATIENTS

Background. Preoperative ejection fraction (EF) has been shown to adve rsely affect postoperative hospital mortality and morbidity for patien ts undergoing isolated coronary artery bypass grafting. Methods. To in vestigate influence of EF on isolated coronary artery bypass grafting outcomes (overall hospital mortality, hospital cardiac mortality, hosp ital morbidity, and hospital costs), data were reviewed from 1,354 con secutive patients who underwent isolated coronary artery bypass grafti ng between January 1, 1990, and April 30, 1992, at a single nonprofit hospital. Overall hospital mortality was 4.06% (cardiac, 2.36%). Hospi tal morbidity was 14.25% (including mortality). Hospital costs (not ch arges) averaged $16,673 per patient. To explore the impact of preopera tive EF, EF was stratified into regular intervals. Each interval was t hen compared with regard to hospital mortality, morbidity, and average costs. A new statistical tool, discharge analysis, was developed to a nalyze the cost data. This was necessary because previous efforts at c ost analysis have used tools inappropriate for real world cost data. R esults. The statistical analysis showed that patients with EF of 0.40 or greater had the best outcomes (lowest mortality, morbidity, and cos t). Once the EF is 0.40 or greater the EF does not carry further predi ctive value. At EF less than 0.40, patients with EF less than 0.30 hav e a poorer outcome than patients with EF of 0.30 to 0.39. Conclusions. (1) Ejection fraction is a valid predictor of mortality, morbidity an d resource utilization based on statistical analysis. (2) Patients can be broadly grouped as having EF greater than 0.40, less than 0.30, or from 0.30 to 0.39 with regard to clinical and cost outcomes. (3) Post operative length of stay is not predicted by risk-adjusted EF. (4) A n ew tool, discharge analysis, is presented to facilitate cost analysis.