Elderly women are more likely than elderly men to die after coronary artery bypass graft surgery (CABG), possibly due to the greater number of postoperative infections suffered by women. A new study found that 16 percent of elderly women compared with 10 percent of elderly men hospitalized for CABG developed an infection during their hospital stay. Greater infection rates among women persisted regardless of age, race, type of admission, hospital volume of CABG surgeries, or presence of other medical conditions.
Overall, CABG patients who developed an infection were 3 times as likely to die in the hospital as those without an infection (12 vs. 4 percent), while twice as many died within 30 days of surgery (9 vs. 4.5 percent). Mortality within the 100-day period after CABG surgery was 16.5 percent for those with an infection compared with 6.2 percent for those without an infection. Men who developed an infection were 3 times more likely to die than men without an infection. On the other hand, women who developed an infection were 1.8 times more likely to die than uninfected women.
The unadjusted excess number of deaths due to female sex in the group of CABG patients studied was 95, which decreased to 4 after adjustment for postoperative infection. Thus, 96 percent of the excess deaths in women could be explained by the underlying differences in infection between men and women. Among all patients, respiratory tract infections were most common (7.4 percent of patients), followed by urinary tract infections (4.7 percent), and digestive tract infections (2.2 percent). The overall prevalence of infection increased with hospital length of stay, from 2.6 percent among those who spent less than 5 days in the hospital to 33.4 percent among those with stays of more than 12 days. These findings were based on a study of 9,218 Michigan Medicare beneficiaries hospitalized for CABG. The study was supported in part by the Agency for Healthcare Research and Quality (HS11540).
See "Contribution of infection to increased mortality in women after cardiac surgery," by Mary A. Rogers, Ph.D., Kenneth M. Langa, M.D., Ph.D., Catherine Kim, M.D., M.P.H., and others in the February 27, 2006, Archives of Internal Medicine 166, pp. 437-443.