Effect of patient sex on intensive care unit survival

Background: Human observations have shown different mortality rates between men and women with various pathological conditions, but this issue has not been widely studied in a heterogeneous population of critically ill patients. Methods: Retrospective analysis of all patients admitted to a mixed medical-surgical, 31-bed intensive care unit (ICU) during 2 different years (1983 and 1995) to evaluate possible differences in mortality between male and female patients and between medical and surgical admissions and variations in these differences over time. Results: From a total of 4420 admissions (1587 women, 2833 men), women showed a higher mortality, with an odds ratio (OR) of 1.18 (95% confidence interval [CI], 1.02-1.38). This pattern was the same for the 2 periods, and all patient data were therefore analyzed together. After age stratification, the differences were significant for female patients older than 50 years (OR, 1.33; 95% Cl, 1.12-1.58) but not in the younger age group. The subgroup of medical admissions had a higher mortality (24.4% vs 7.4%, P < .001) and a higher female proportion (37.9% vs 34.2%, P = .01) than surgical admissions. In multivariate analysis, female sex remained an important predictor of mortality (OR, 1.54; 95% Cl, 1.25-1.89). Women had a higher mortality than men in the subgroup of cardiovascular diseases. The highest mortality in female patients was present in the first days after admission and decreased over time, showing a covariance of time and sex. Conclusions: In a mixed medical-surgical ICU, older women have a higher mortality rate than men. This difference is not apparent for patients staying longer in the ICU.