title: Ensemble-based methods for forecasting census in hospital units.
abstract: BACKGROUND
  The ability to accurately forecast census counts in hospital departments has considerable implications for hospital resource allocation. In recent years several different methods have been proposed forecasting census counts, however many of these approaches do not use available patient-specific information.
  
  
  METHODS
  In this paper we present an ensemble-based methodology for forecasting the census under a framework that simultaneously incorporates both (i) arrival trends over time and (ii) patient-specific baseline and time-varying information. The proposed model for predicting census has three components, namely: current census count, number of daily arrivals and number of daily departures. To model the number of daily arrivals, we use a seasonality adjusted Poisson Autoregressive (PAR) model where the parameter estimates are obtained via conditional maximum likelihood. The number of daily departures is predicted by modeling the probability of departure from the census using logistic regression models that are adjusted for the amount of time spent in the census and incorporate both patient-specific baseline and time varying patient-specific covariate information. We illustrate our approach using neonatal intensive care unit (NICU) data collected at Women & Infants Hospital, Providence RI, which consists of 1001 consecutive NICU admissions between April 1st 2008 and March 31st 2009.
  
  
  RESULTS
  Our results demonstrate statistically significant improved prediction accuracy for 3, 5, and 7 day census forecasts and increased precision of our forecasting model compared to a forecasting approach that ignores patient-specific information.
  
  
  CONCLUSIONS
  Forecasting models that utilize patient-specific baseline and time-varying information make the most of data typically available and have the capacity to substantially improve census forecasts.
authors.affiliation: Department of Community and Family Medicine, Geisel School of Medicine at Dartmouth College, Lebanon, NH 03756, USA. devin.c.koestler@dartmouth.edu
authors.forename: Devin C
authors.initials: DC
authors.lastname: Koestler
authors.forename: Hernando
authors.initials: H
authors.lastname: Ombao
authors.forename: Jesse
authors.initials: J
authors.lastname: Bender
mesh_terms: D000328:Adult; D019352:Censuses; D005260:Female; D005544:Forecasting / Q000379:methods*; D006757:Hospital Units / Q000706:statistics & numerical data*; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal / Q000706:statistics & numerical data; D010343:Patient Admission / Q000706:statistics & numerical data; D016012:Poisson Distribution; D012237:Rhode Island