The hospital mortality of patients admitted to the ICU on weekends

Study objectives: Previous studies have suggested that patients are more likely to die in the hospital if they are admitted on a weekend than on a weekday. This study was conducted to determine whether weekend admission to the ICU increases the risk of dying in the hospital. Design: Retrospective cohort study. Setting: ICU of a single tertiary care medical center. Patients: A total of 29,084 patients admitted to medical, surgical, and multispecialty ICUs from October 1994 through September 2002. Interventions: None. Measurements and results: The weekend ICU admissions comprised 27.9% of all ICU admissions (8,108 ICU admissions). The overall hospital mortality rate was 8.2% (2,385 deaths). Weekend ICU admission was associated with a higher unadjusted hospital mortality rate than that for weekday ICU admission (11.3% vs 7.0%, respectively; odds ratio [OR], 1.70; 95% confidence interval [CI], 1.55 to 1.85). In multivariable analyses controlling for the factors associated with mortality such as APACHE (acute physiology and chronic health evaluation) III predicted mortality rate, ICU admission source, and intensity of treatment, no statisticatly significant difference in hospital mortality was found between weekend and weekday admissions in the overall study population (OR, 1.06; 95% CI, 0.95 to 1.17). For weekend ICU admissions, the observed hospital mortality rates of the medical, multispecialty, and surgical ICUs were 15.2%, 17.2%, and 6.4%, respectively, and for weekday ICU admissions the rates were 16.3%, 10.1%, and 3.5%, respectively. Subgroup analyses showed that weekend ICU admission was associated with higher adjusted hospital mortality rates than was weekday ICU admission in the surgical ICU (OR, 1.23; 95% CI, 1.03 to 1.48), but not in the medical or multispecialty ICUs. Conclusions: The overall adjusted hospital mortality rate of patients admitted to the ICU on a weekend was not higher than that of patients admitted on a weekday. However, weekend ICU admission to the surgical ICU was associated with an increased hospital mortality rate.