title: Time-weighted nursing demand is a better predictor than midnight census of nursing supply in an intensive care unit.
abstract: OBJECTIVE
  Labor costs are the largest fraction of operating costs in an intensive care unit (ICU). Estimation of appropriate nursing supply is frequently based on the midnight census of patients, which is a "snapshot" view of the ICU. We postulated that the midnight census would not correlate as well as time-weighted nursing demand (a calculation of need for nursing staff) with the actual number of nurses who were required to staff the ICU (nursing supply). The purpose of this study was to compare the correlation between midnight census and actual nursing supply with the correlation between time-weighted nursing demand and nursing supply.
  
  
  METHODS
  We measured nursing activity, midnight census, and actual nursing supply for each of 77 consecutive days in a 14-bed medical-surgical ICU within a 450-bed tertiary care teaching hospital. We calculated time-weighted nursing demand based on 1:1 nursing for ICU patients, 1:2 nursing for step-down patients, 0.5 additional nurse hours for each cardiac arrest, and 0.5 additional nurse hours for each new admission to the ICU.
  
  
  RESULTS
  There was a correlation between midnight census and nursing supply (r2 = .42, P<.0001) and between nursing demand and nursing supply (r2 = .83, P<.0001). The correlation coefficient for the relationship between nursing demand and nursing supply was significantly greater than that for the relationship between midnight census and nursing supply (P<.01).
  
  
  CONCLUSIONS
  Time-weighted nursing demand is a better predictor than midnight census of nursing supply in an ICU.
authors.affiliation: Department of Medicine and Center for Health Evaluation and Outcome Sciences, St. Paul's Hospital and University of British Columbia, Vancouver, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Volpatti
authors.forename: M
authors.initials: M
authors.lastname: Leathley
authors.forename: K R
authors.initials: KR
authors.lastname: Walley
authors.forename: P M
authors.initials: PM
authors.lastname: Dodek
mesh_terms: D001955:British Columbia; D003363:Cost Control; D005544:Forecasting; D017721:Hospital Costs; D006801:Humans; D007362:Intensive Care Units / Q000191:economics; D008962:Models, Theoretical; D009741:Nursing Staff, Hospital / Q000191:economics / Q000600:supply & distribution*; D010561:Personnel Staffing and Scheduling / Q000191:economics; D013997:Time Factors; D000078329:Workforce; D016526:Workload