Mortality rate after nonelective hospital admission.

Objective: We hypothesized that the mortality rate after nonelective hospital admission is higher during weekends than weekdays.

Design: Retrospective cohort analysis.

Setting: Patients admitted to hospitals in the Nationwide Inpatient Sample, a 20% sample of US community hospitals.

Patients: We identified all patients with a nonelective hospital admission from January 1, 2003, through December 31, 2007, in the Nationwide Inpatient Sample. Next, we abstracted vital status at discharge and calculated the Charlson comorbidity index score for all patients. We then compared odds of inpatient mortality after nonelective hospital admission during the weekend compared with weekdays, after adjusting for diagnosis, age, sex, race, income level, payer, comorbidity, and hospital characteristics.

Main Outcome Measure: Mortality rate.

Results: Discharge data were available for 29,991,621 patients with nonelective hospital admissions during the 5-year study period: 6,842,030 during weekends and 23,149,591 during weekdays. Inpatient mortality was reported in 185,856 patients (2.7%) admitted for nonelective indications during weekends and 540,639 (2.3%) during weekdays (P < .001). The regression revealed significantly higher mortality during weekends for 15 of 26 (57.7%) major diagnostic categories. The weekend effect remained, and mortality was noted to be 10.5% higher during weekends (odds ratio, 1.10; 95% confidence interval, 1.10-1.11) compared with weekdays after adjusting for all other variables with the imputed data set.

Conclusions: These data demonstrate significantly worse outcomes after nonelective admission during the weekend compared with weekdays. Although the underlying mechanism of this finding is unknown, it is likely that factors such as differences in hospital staffing and services offered during the weekend compared with weekdays are causal and mutable.