Differences Between Men andWomen in Hospital Mortalit Associated WithCoronary Artery Bypass Graft Surgery

Background. Aprospective study ofpatients undergoing coronaryartery bypass graft surgery(CABG) wasconducted toexamine differences inhospital mortality bysex.Outcome data on3055CABGpatients undergoing operation between 1987and1989 wereexamined fordifferences inpatient, disease, and treatment factors. Methods and Results. Oddsratios (OR), riskdifferences, and95%confidence intervals (CI95%) were calculated. Mortality rates for women (7.1%) andmen (3.3%) differed, theOR(women versusmen)being 2.23(CI9%, 1.58 to3.15). Womenwereolder, more often diabetic, andhadmore urgent or emergent surgery;adjustment yielded an OR (women versusmen)of1.75(CI95%, 1.17to2.63). Bodysurface area (BSA) was associated withriskofdeathinbothsexes(P=.007) andpositively associated with coronary artery luminal diameters. Afteradjustment forBSA,sexwas no longer significantly associated with mortality (OR[women versusmen]of1.18; CI95%, 0.72 to1.95). Internal mammary artery (IMA)grafting was performed less frequently among women thanmen (64.8% versus78.4%, P<.001). Smaller BSAand absence ofIMAgrafting wereeachassociated withincreased risk ofdeath(RD)fromheart failure. Risk ofdeathfromheart failure (RD[womenminusmen]= 2.05; CI95%, 0.89to3.22) andhemorrhage (RD [womenminusmen]= 0.63; CI5%, 0.13to1.13) was greater among women; these accounted for71.1%of thesex-specific difference inmortality rates. Conclusions. Excess riskofhospital mortality amongwomen having CABGwaslargely theconsequence ofdeathfromheart failure and,toalesser extent, fromhemorrhage. Smaller BSA(probably because of itsassociation withcoronaryartery luminal diameter) andtheabsence ofIMA grafting were each associated withincreased riskofdeathfromheart failure. (Circulation. 1993;88[part 11:2104-2110.)