title: Distribution of outbreak reporting in health care institutions by day of the week.
abstract: BACKGROUND
  The notion that outbreaks are more likely to occur on Friday is prevalent among staff in health care institutions. However, there is little evidence to support or discredit this notion. We postulated that outbreaks were no more likely to be reported on any particular day of the week.
  
  
  METHODS
  A total of 901 institutional outbreaks in Toronto health care facilities were tabulated according to type, outbreak setting, and day of the week reported. A χ(2) goodness-of-fit test compared daily values for 7-day per week and 5-day per week periods. Post hoc partitioning was used to pinpoint specific day(s) of the week that differed significantly.
  
  
  RESULTS
  Fewer outbreaks were reported on Saturdays and Sundays. Further analysis examined the distribution of outbreak reporting specifically focusing on the Monday to Friday weekday period. Among the weekdays, higher proportions of outbreaks were reported on Mondays and Fridays.
  
  
  CONCLUSIONS
  Our null hypothesis was rejected. Overall, Mondays and Fridays had the highest occurrence of outbreak reporting. We suggest that this might be due to "deadline" and "catch-up" reporting related to the "weekend effect," whereby structural differences in weekend staffing affect detection of outbreaks. Such delays warrant reexamination of surveillance processes for timely outbreak detection independent of calendar cycle.
authors.affiliation: Infection Prevention and Control, Baycrest Geriatric Healthcare System, Toronto, Ontario, Canada. camirov@baycrest.org
authors.forename: Chingiz
authors.initials: C
authors.lastname: Amirov
authors.forename: Ryan N
authors.initials: RN
authors.lastname: Walton
authors.forename: Sarah
authors.initials: S
authors.lastname: Ahmed
authors.forename: Malcolm A
authors.initials: MA
authors.lastname: Binns
authors.forename: Jane E
authors.initials: JE
authors.lastname: Van Toen
authors.forename: Heather L
authors.initials: HL
authors.lastname: Candon
mesh_terms: D002170:Canada / Q000453:epidemiology; D003428:Cross Infection / Q000453:epidemiology*; D018563:Disease Notification / Q000706:statistics & numerical data*; D004196:Disease Outbreaks; D006268:Health Facilities; D006801:Humans; D012308:Risk Management / Q000706:statistics & numerical data*; D013997:Time Factors