title: Off hour admission to an intensivist-led ICU is not associated with increased mortality.
abstract: BACKGROUND
  Caring for the critically ill is a 24-hour-a-day responsibility, but not all resources and staff are available during off hours. We evaluated whether intensive care unit (ICU) admission during off hours affects hospital mortality.
  
  
  METHODS
  This retrospective multicentre cohort study was carried out in three non-academic teaching hospitals in the Netherlands. All consecutive patients admitted to the three ICUs between 2004 and 2007 were included in the study, except for patients who did not fulfil APACHE II criteria (readmissions, burns, cardiac surgery, younger than 16 years, length of stay less than 8 hours). Data were collected prospectively in the ICU databases. Hospital mortality was the primary endpoint of the study. Off hours was defined as the interval between 10 pm and 8 am during weekdays and between 6 pm and 9 am during weekends. Intensivists, with no responsibilities outside the ICU, were present in the ICU during daytime and available for either consultation or assistance on site during off hours. Residents were available 24 hours a day 7 days a week in two and fellows in one of the ICUs.
  
  
  RESULTS
  A total of 6725 patients were included in the study, 4553 (67.7%) admitted during daytime and 2172 (32.3%) admitted during off hours. Baseline characteristics of patients admitted during daytime were significantly different from those of patients admitted during off hours. Hospital mortality was 767 (16.8%) in patients admitted during daytime and 469 (21.6%) in patients admitted during off hours (P < 0.001, unadjusted odds ratio 1.36, 95%CI 1.20-1.55). Standardized mortality ratios were similar for patients admitted during off hours and patients admitted during daytime. In a logistic regression model APACHE II expected mortality, age and admission type were all significant confounders but off-hours admission was not significantly associated with a higher mortality (P = 0.121, adjusted odds ratio 1.125, 95%CI 0.969-1.306).
  
  
  CONCLUSIONS
  The increased mortality after ICU admission during off hours is explained by a higher illness severity in patients admitted during off hours.
authors.affiliation: ICU, Reinier de Graaf Groep, Reinier de Graafweg 3-11, 2625 AD Delft, Netherlands. meynaar@rdgg.nl
authors.forename: Iwan A
authors.initials: IA
authors.lastname: Meynaar
authors.forename: Johan I
authors.initials: JI
authors.lastname: van der Spoel
authors.forename: Johannes H
authors.initials: JH
authors.lastname: Rommes
authors.forename: Margot
authors.initials: M
authors.lastname: van Spreuwel-Verheijen
authors.forename: Rob J
authors.initials: RJ
authors.lastname: Bosman
authors.forename: Peter E
authors.initials: PE
authors.lastname: Spronk
mesh_terms: D039602:After-Hours Care / Q000706:statistics & numerical data; D000368:Aged; D005260:Female; D017052:Hospital Mortality; D006784:Hospitals, Teaching; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D010561:Personnel Staffing and Scheduling; D011787:Quality of Health Care; D012189:Retrospective Studies