B40-01 Illness Severity Modifies The Association Between Weekend Admission And In-hospital Mortality: A Nationwide Cohort Study

Background

The association between weekend hospital admission and in-hospital mortality remains controversial after risk adjustment. Prior studies have largely treated the “weekend effect” as a uniform phenomenon, with limited evaluation of whether this association varies according to illness severity and the need for critical respiratory care.

Methods

We conducted a retrospective cohort study of 9,658,351 adult hospitalizations from a nationwide inpatient database. The primary outcome was in-hospital mortality. Multivariable logistic regression was used to assess the association between weekend admission and mortality, adjusting for age, sex, primary expected payer, and comorbidity burden quantified by the number of ICD-10 diagnoses. Critical respiratory intervention was used as an operational proxy for illness severity. Effect modification was evaluated using an interaction term between weekend admission and critical respiratory intervention. Adjusted odds ratios (aORs) with 95% confidence intervals (CIs) were reported. Data analysis was performed using IBM SPSS Statistics 25.0.

Results

Overall in-hospital mortality was 5.7%. Among patients not requiring critical respiratory intervention, weekend admission was associated with lower adjusted odds of in-hospital mortality (aOR 0.95, 95% CI 0.94-0.96). In contrast, among patients requiring critical respiratory intervention, weekend admission was associated with higher mortality, as demonstrated by a significant interaction effect (interaction aOR 1.39, 95% CI 1.37-1.41, p < 0.001). Critical respiratory intervention was independently associated with increased mortality (aOR 2.02, 95% CI 2.00-2.03)

Conclusions

In this nationwide cohort, the association between weekend admission and in-hospital mortality was not uniform but strongly modified by illness severity. While weekend admission was associated with lower mortality among less severe patients, it was associated with higher mortality among patients requiring critical respiratory intervention. These findings highlight the importance of severity-adjusted and condition-specific analyses when evaluating hospital performance and suggest that system-level factors during weekend care may disproportionately affect patients with severe respiratory illness.

This abstract is funded by: none