Stratification of morbidity and mortality outcome by preoperative risk factors in coronary artery bypass patients. A clinical severity score.
OBJECTIVE
To relate morbidity and mortality risk to preoperative severity of illness in patients undergoing coronary artery bypass grafting.


METHODS
Retrospective analysis of 5051 patients using univariate and logistic regression to identify risk factors associated with perioperative morbidity and mortality. Prospective application of models to a subsequent 2-year validation cohort (n = 4069).


METHODS
Cleveland Clinic Foundation.


METHODS
All adult patients undergoing coronary artery bypass graft surgery between July 1, 1986, and June 30, 1988 (reference group), and July 1, 1988, and June 30, 1990 (validation group).


METHODS
Mortality and morbidity (myocardial infarction and use of intra-aortic balloon pump, mechanical ventilation for 3 or more days, neurological deficit, oliguric or anuric renal failure, or serious infection).


RESULTS
Emergency procedure, preoperative serum creatinine levels of greater than 168 mumol/L, severe left ventricular dysfunction, preoperative hematocrit of 0.34, increasing age, chronic pulmonary disease, prior vascular surgery, reoperation, and mitral valve insufficiency were found to be predictive of mortality. In addition to these factors, diabetes mellitus, body weight of 65 kg or less [corrected], aortic stenosis, and cerebrovascular disease were predictive of morbidity. Logistic regression equations were developed, and a simple additive score for clinical use was designed by allocating each of these risk-factor values of 1 to 6 points. Both methods predict mortality. Increased morbidity was demonstrated with increases in score.


CONCLUSIONS
The logistic or clinical models developed are superior to the currently available methods for comparing mortality outcome and provide previously unavailable information on morbidity based on preoperative status. The clinical scoring system is useful for preoperative estimates of morbidity and mortality risks.
Higgins
T L
TL
Department of Cardiothoracic Anesthesiology, Cleveland Clinic Foundation, OH.
Estafanous
F G
FG
Loop
F D
FD
Beck
G J
GJ
Blum
J M
JM
Paranandi
L
L
D000368:Aged; D001026:Coronary Artery Bypass / Q000401:mortality*; D005260:Female; D006761:Hospitals; D006801:Humans; D016015:Logistic Models; D008297:Male; D009017:Morbidity; D017063:Outcome Assessment, Health Care / Q000379:methods*; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014481:United States