Weekend hospital admission, acute kidney injury, and mortality

Abstract

Admission to the hospital on weekends is associated with increased mortality for several acute illnesses. We investigated whether patients admitted on a weekend with acute kidney injury (AKI) were more likely to die than those admitted on a weekday. Using the Nationwide Inpatient Sample, a large database of admissions to acute care, nonfederal hospitals in the United States, we identified 963,730 admissions with a diagnosis of AKI between 2003 and 2006. Of these, 214,962 admissions (22%) designated AKI as the primary reason for admission (45,203 on a weekend and 169,759 on a weekday). We used logistic regression models to examine the adjusted odds of in-hospital mortality associated with weekend versus weekday admission. Compared with admission on a weekday, patients admitted with a primary diagnosis of AKI on a weekend had a higher odds of death [adjusted odds ratio (OR) 1.07, 95% confidence interval (CI) 1.02 to 1.12]. The risk for death with admission on a weekend for AKI was more pronounced in smaller hospitals (adjusted OR 1.17, 95% CI 1.03 to 1.33) compared with larger hospitals (adjusted OR 1.07, 95% CI 1.01 to 1.13). Increased mortality was also associated with weekend admission among patients with AKI as a secondary diagnosis across a spectrum of co-existing medical diagnoses. In conclusion, among patients hospitalized with AKI, weekend admission is associated with a higher risk for death compared with admission on a weekday.

Figure 1.

Higher mortality for primary diagnosis of AKI with weekend versus weekday admission by hospital day 3 (A) and during total hospital stay (B), most pronounced in smaller hospitals.

Figure 2.

Higher mortality for weekend versus weekday admission across multiple primary acute conditions with AKI as secondary diagnosis (OR adjusted for age, sex, race, Charlson comorbidity index, and use of mechanical ventilation).