Absence of a Weekend Effect on In-Hospital Mortality in Upper Gastrointestinal Bleeding: A Multisite Study from an Integrated Health System

Technical Summary: Absence of a Weekend Effect on In-Hospital Mortality in Upper Gastrointestinal Bleeding

Problem Statement
The "weekend effect"—the observation that patients admitted to acute-care hospitals on Saturdays or Sundays experience worse outcomes than those admitted on weekdays—has been documented across various acute conditions, including upper gastrointestinal bleeding (UGIB). Historically, this disparity has been attributed to reduced staffing levels, delayed access to specialized procedural services (specifically endoscopy), attenuated senior supervision, and slower diagnostic turnaround during weekends. While previous studies, including analyses of the Nationwide Inpatient Sample and systematic reviews, have confirmed higher weekend mortality for UGIB (particularly in nonvariceal bleeding), it remains uncertain whether this disparity persists in contemporary, integrated health systems that utilize standardized care pathways and maintain continuous endoscopy availability.

Methodology
The authors conducted a retrospective multicenter cohort study within the Northwell Health system, the largest integrated health system in New York State.

• Study Population: The cohort included 7,640 adults (aged 18–89) admitted between January 1, 2019, and January 31, 2024, with a primary or secondary diagnosis of UGIB.
• Exposure Definition: Weekend admission was defined as arrival between 00:00 Saturday and 23:59 Sunday.
• Outcomes: The primary outcome was in-hospital mortality. Secondary outcomes included intensive care unit (ICU) admission, length of stay (LOS), and 30-day readmission.
• Statistical Approach: The study utilized chi-square and Wilcoxon rank-sum tests for unadjusted comparisons. A multivariable logistic regression model was constructed to assess the independent association between weekend admission and mortality. Crucially, the model included weekend admission (forced entry), age, liver cirrhosis, and shock. The authors deliberately excluded in-hospital management variables (e.g., time to endoscopy, transfusion, rebleeding) from the primary model to avoid "mediator adjustment," which would bias the estimated effect of admission timing toward the null.
• Data Handling: Missing data were minimal and handled via complete-case analysis. The study adhered to STROBE guidelines.

Key Results

• Cohort Characteristics: Of the 7,640 patients, 25.2% (1,927) were admitted on weekends. Baseline characteristics were broadly similar between groups, with the exception of liver cirrhosis, which was slightly more frequent in the weekend group (8.0% vs. 6.5%, P = 0.03).
• Primary Outcome (Mortality): The overall in-hospital mortality rate was 5.5% (421/7,640). There was no statistically significant difference in mortality between weekend and weekday admissions (5.5% for both). In the multivariable model, weekend admission was not associated with increased mortality (adjusted odds ratio [aOR] 1.06; 95% CI 0.83–1.35; P = 0.67).
• Predictors of Mortality: The dominant determinants of mortality were disease severity markers rather than admission timing. Shock conferred a massive increase in mortality risk (aOR 19.08; 95% CI 15.33–23.76), followed by liver cirrhosis (aOR 1.81; 95% CI 1.23–2.67) and age (aOR 1.04 per year).
• Secondary Outcomes: No significant differences were observed between weekend and weekday admissions regarding ICU admission rates (23.3% vs. 21.9%), median length of stay (4.49 vs. 4.66 days), or 30-day readmission rates (1.8% vs. 2.3%).

Significance and Claims
The paper posits that within a large, integrated health system equipped with standardized GI bleed pathways, continuous endoscopy availability, and protocolized resuscitation, the historical "weekend effect" in UGIB outcomes has been eliminated. The authors argue that their findings provide positive evidence that system-level interventions can deliver equivalent care across the temporal continuum, effectively neutralizing the disparities previously attributed to reduced after-hours resources.

The study highlights that disease severity—specifically hemodynamic instability (shock) and underlying liver pathology (cirrhosis)—is the primary driver of mortality, far outweighing the impact of the day of admission. The authors conclude that continued investment in system-level quality infrastructure, rather than merely redistributing weekday resources, is central to sustaining equitable outcomes in UGIB management. They note that while their results align with some recent studies showing attenuated weekend effects, they contrast with earlier reports of persistent disparities, suggesting that structural standardization is the key differentiator.

Limitations Acknowledged
The authors acknowledge the retrospective observational nature of the study, which precludes causal inference and leaves potential for unmeasured confounding (e.g., specific bleeding etiology, anticoagulant use). They also note that generalizability may be limited to institutions with similar continuous coverage and infrastructure, and that the study did not stratify results by bleeding source (variceal vs. nonvariceal) or examine holiday admissions.