The Effects of Weekend Admission on the Mortality of Patients Admitted to Intensive Care Units: The Role of Organizational Factors

Afiliações: 1Hospital do Coração, São Paulo, Brazil; 2Santa Casa de Misericórdia, Porto Alegre, Brazil, 3D’Or Institute for Research and Education, Rio de Janeiro, Brazil.

Introdução: Weekend admission is considered a risk factor for worse outcomes in critically ill patients, but more robust information on the underlying mechanisms related to intensive care unit (ICU) organization is still lacking. We assessed whether ICU organizational and staffing patterns could explain the association between weekend admission and outcomes in critically ill patients.

Métodos: Retrospective cohort study using the ORCHESTRA study database [1] comprising 59,614 patients admitted to the participant ICUs during 2013. The association between weekend admission and hospital mortality was assessed using mixed logistic regression adjusting for clinically relevant patient-level (age, severity of organ dysfunctions, comorbidities, performance status; admission type and length of hospital stay before ICU admission) and ICU-level (use of checklists on weekend; 24/7 full-time intensivists; nurse/bed ratio; unit type and number of protocols) characteristics.

Resultados: 41,894 patients (70.3%) were admitted on weekdays and 17,720 patients (29.7%) were admitted on weekends. In univariate analysis, weekend admitted patients had higher ICU (10.9% vs. 9.0%, p<0.001) and hospital (16.5% vs. 13.5%, p<0.001) mortality rates. After regression, weekend admission was not associated with higher hospital mortality (OR 1.05, 95% CI 0.99-1.12, p=0.095). However, a “weekend effect” was still observed in scheduled surgical patients, as well as in ICUs not holding checklists and with a decrease in nurse/bed ratio during the weekends. In addition, units with a lower number of implemented protocols had also higher mortality for patients admitted during the weekends. For unscheduled admissions, no “weekend effect” was observed regardless of ICU´s characteristics.

Conclusão: Weekend admissions were associated with higher mortality in certain situations related to potentially modifiable patients’ and centers’ features, representing an opportunity to improve ICU performance and patients’ outcomes.

1. Soares M, Bozza FA, Angus DC, et al. Organizational characteristics, outcomes, and resource use in 78 Brazilian intensive care units: the ORCHESTRA study. Intensive Care Med. 2015 Dec;41(12):2149-60.