title: Determinants of per diem Hospital Costs in Mental Health.
abstract: BACKGROUND
  An understanding of differences in hospital costs between patient groups is relevant for the efficient organisation of inpatient care. The main aim of this study was to confirm the hypothesis that eight a priori identified cost drivers influence per diem hospital costs. A second aim was to explore further variables that might influence hospital costs.
  
  
  METHODS
  The study included 667 inpatient episodes consecutively discharged in 2014 at the psychiatric hospital of the Medical Centre-University of Freiburg. Fifty-one patient characteristics were analysed. Per diem costs were calculated from the hospital perspective based on a detailed documentation of resource use. Mixed-effects maximum likelihood regression and an ensemble of conditional inference trees were used to analyse data.
  
  
  RESULTS
  The study confirmed the a priori hypothesis that not being of middle age (33-64 years), danger to self, involuntary admission, problems in the activities of daily living, the presence of delusional symptoms, the presence of affective symptoms, short length of stay and the discharging ward affect per diem hospital costs. A patient classification system for prospective per diem payment was suggested with the highest per diem hospital costs in episodes having both delusional symptoms and involuntary admissions and the lowest hospital costs in episodes having neither delusional symptoms nor somatic comorbidities.
  
  
  CONCLUSIONS
  Although reliable cost drivers were identified, idiosyncrasies of mental health care complicated the identification of clear and consistent differences in hospital costs between patient groups. Further research could greatly inform current discussions about inpatient mental health reimbursement, in particular with multicentre studies that might find algorithms to split patients in more resource-homogeneous groups.
authors.affiliation: King's College London, Institute of Psychiatry, Psychology & Neuroscience, King's Health Economics, De Crespigny Park, London, United Kingdom.|Medical Centre-University of Freiburg, Department for Management and Controlling, Freiburg, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Wolff
authors.affiliation: King's College London, Institute of Psychiatry, Psychology & Neuroscience, King's Health Economics, De Crespigny Park, London, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: McCrone
authors.affiliation: King's College London, Institute of Psychiatry, Psychology & Neuroscience, King's Health Economics, De Crespigny Park, London, United Kingdom.|Queen Mary University of London, Barts and the London School of Medicine and Dentistry, Centre for Primary Care and Public Health, London, United Kingdom.
authors.forename: Anita
authors.initials: A
authors.lastname: Patel
authors.affiliation: Medical Centre- University of Freiburg, Department of Psychiatry and Psychotherapy, Freiburg, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Normann
mesh_terms: D000328:Adult; D005260:Female; D005858:Germany; D017721:Hospital Costs; D006778:Hospitals, Psychiatric; D006801:Humans; D007297:Inpatients; D007902:Length of Stay; D016013:Likelihood Functions; D008297:Male; D001523:Mental Disorders / Q000191:economics; D008603:Mental Health / Q000191:economics*; D008875:Middle Aged