INCREASED RISK AND DECREASED MORBIDITY OF CORONARY-ARTERY BYPASS-GRAFTING BETWEEN 1986 AND 1994

Background. The collective impact of advances in medical, surgical, an d anesthetic care on the characteristics and outcomes of patients who undergo coronary artery bypass grafting was assessed. Methods. We comp ared the demographic and clinical characteristics, preoperative risk f actors, morbidity, and mortality of two groups of patients who underwe nt coronary artery bypass grafting in isolation or in combination with other procedures between July 1, 1986, and June 30, 1988 (group 1, n = 5,051), and between January 1, 1993, and March 31, 1994 (group 2, n = 2,793). The patients were stratified according to their preoperative risk level. Outcome measures consisted of changes in preoperative ris k categories; hospital mortality rates; overall and risk-adjusted majo r cardiac, neurologic, pulmonary, renal, and septic morbidity rates; a nd intensive care unit length of stay. Results. Changes in the distrib ution of risk categories, from a median of 2 to 4 on a 9-point scale ( p < 0.001), indicated that patients in group 2 were at significantly h igher risk than those in group 1. The risk-adjusted mortality rate did not change (2.8% to 2.9%; p = 0.15), but the risk-adjusted morbidity rate decreased significantly (14.5% to 8.8%; p < 0.001). Conclusions. At our institution, patients who undergo coronary artery bypass grafti ng are now at greater preoperative risk at the time of hospital admiss ion. However, their morbidity rate is significantly lower and their mo rtality rate is unchanged, results that we attribute to the collective impact of changes in our medical and surgical procedures.