Day and time of admissions to intensive care units - does it matter?

Background: The literature data pertaining to the significance of day and time of ICU admission for outcomes of patients are inconsistent. The issue has not been analysed in Poland to date. The aim of the study was to gather information about differences between patients admitted to ICU outside regular working hours (off-hours) and those admitted during working hours (on-hours).
Methods: Analysis involved 20,651 patients from the Silesian Registry of Intensive Care Units carried out since 2010. The findings demonstrated that 34.8% of patients were admitted to ICUs during on-hours (between 8.00 a.m. and 3 p.m. on weekdays) and 65.2% were admitted during off-hours (outside regular working hours). The incidence of admissions and data of patients in both groups were compared in terms of the population characteristics and treatment outcomes.
Results: The incidence of admissions (calculated per each 24 hours of treatment) was found to be almost twice as high during on-hours, as compared to off-hours (14.5 vs. 6.9 patients/day). Patients admitted to the ICU during on-hours were less likely to be admitted from the surgical department (19.1% vs. 31.0%, P < 0.001), and more likely to be admitted from the emergency department (25.3% vs. 14.2%, P < 0.001). The incidence of off-hours admissions of cancer patients was lower (5.3% vs. 10.8%, P < 0.001), as compared with patients with alcohol dependence syndrome (10.3% vs. 6.9%, P < 0.001). Patients admitted during off-hours were in more severe conditions and had higher APACHE II scores (on average, 23.8 ± 8.8 vs. 21.8 ± 8.8, P < 0.001); their mortality rates were higher compared to the remaining population (46.8% vs. 39.4%, P < 0.001).
Conclusions: Patients admitted to ICUs during off-hours are in more severe general condition and their treatment outcomes are worse, as compared to patients admitted to ICU during on-hours.