title: Impact of integrated health system changes, accelerated due to an earthquake, on emergency department attendances and acute admissions: a Bayesian change-point analysis.
abstract: To chart emergency department (ED) attendance and acute admission following a devastating earthquake in 2011 which lead to Canterbury's rapidly accelerated integrated health system transformations.
  
  
  
  Interrupted time series analysis, modelling using Bayesian change-point methods, of ED attendance and acute admission rates over the 2008-2014 period.
  
  
  
  ED department within the Canterbury District Health Board; with comparison to two other district health boards unaffected by the earthquake within New Zealand.
  
  
  
  Canterbury's health system services ∼500 000 people, with around 85 000 ED attendances and 37 000 acute admissions per annum.
  
  
  
  De-seasoned standardised population ED attendance and acute admission rates overall, and stratified by age and sex, compared before and after the earthquake.
  
  
  
  Analyses revealed five global patterns: (1) postearthquake, there was a sudden and persisting decrease in the proportion of the population attending the ED; (2) the growth rate of ED attendances per head of population did not change between the pre-earthquake and postearthquake periods; (3) postearthquake, there was a sudden and persisting decrease in the proportion of the population admitted to hospital; (4) the growth rate of hospital admissions per head of the population declined between pre-earthquake and postearthquake periods and (5) the most dramatic reduction in hospital admissions growth after the earthquake occurred among those aged 65+ years. Extrapolating from the projected and fitted deseasoned rates for December 2014, ∼676 (16.8%) of 4035 projected hospital admissions were avoided.
  
  
  
  While both necessarily and opportunistically accelerated, Canterbury's integrated health systems transformations have resulted in a dramatic and sustained reduction in ED attendances and acute hospital admissions. This natural intervention experiment, triggered by an earthquake, demonstrated that integrated health systems with high quality out-of-hospital care models are likely to successfully curb growth in acute hospital demand, nationally and internationally.
authors.affiliation: School of Health Sciences, University of Canterbury, Christchurch, New Zealand School of Nursing, Midwifery and Social Work, The University of Queensland, Brisbane, Australia.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Schluter
authors.affiliation: Division of Planning and Funding, Canterbury District Health Board, Christchurch, New Zealand.
authors.forename: Greg J
authors.initials: GJ
authors.lastname: Hamilton
authors.affiliation: Canterbury District Health Board, Christchurch, New Zealand.
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Deely
authors.affiliation: Emergency Department, Christchurch Hospital, Christchurch, New Zealand Department of Surgery, University of Otago, Christchurch, Christchurch, New Zealand.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Ardagh
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001499:Bayes Theorem; D002648:Child; D002675:Child, Preschool; D019033:Delivery of Health Care, Integrated / Q000458:organization & administration / Q000706:statistics & numerical data* / Q000639:trends; D055866:Earthquakes; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data* / Q000639:trends; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D065186:Interrupted Time Series Analysis; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D010343:Patient Admission / Q000706:statistics & numerical data* / Q000639:trends; D055815:Young Adult
keywords: Bayesian statistical methods; epidemiological investigation; hospital attendances and admissions; integrated health system