title: Utility of the Health of the Nation Outcome Scales (HoNOS) in Predicting Mental Health Service Costs for Patients with Common Mental Health Problems: Historical Cohort Study.
abstract: BACKGROUND
  Few countries have made much progress in implementing transparent and efficient systems for the allocation of mental health care resources. In England there are ongoing efforts by the National Health Service (NHS) to develop mental health 'payment by results' (PbR). The system depends on the ability of patient 'clusters' derived from the Health of the Nation Outcome Scales (HoNOS) to predict costs. We therefore investigated the associations of individual HoNOS items and the Total HoNOS score at baseline with mental health service costs at one year follow-up.
  
  
  METHODS
  An historical cohort study using secondary care patient records from the UK financial year 2012-2013. Included were 1,343 patients with 'common mental health problems', represented by ICD-10 disorders between F32-48. Costs were based on patient contacts with community-based and hospital-based mental health services. The costs outcome was transformed into 'high costs' vs 'regular costs' in main analyses.
  
  
  RESULTS
  After adjustment for covariates, 11 HoNOS items were not associated with costs. The exception was 'self-injury' with an odds ratio of 1.41 (95% CI 1.10-2.99). Population attributable fractions (PAFs) for the contribution of HoNOS items to high costs ranged from 0.6% (physical illness) to 22.4% (self-injury). After adjustment, the Total HoNOS score was not associated with costs (OR 1.03, 95% CI 0.99-1.07). However, the PAF (33.3%) demonstrated that it might account for a modest proportion of the incidence of high costs.
  
  
  CONCLUSIONS
  Our findings provide limited support for the utility of the self-injury item and Total HoNOS score in predicting costs. However, the absence of associations for the remaining HoNOS items indicates that current PbR clusters have minimal ability to predict costs, so potentially contributing to a misallocation of NHS resources across England. The findings may inform the development of mental health payment systems internationally, especially since the vast majority of countries have not progressed past the early stages of this development. Discrepancies between our findings with those from Australia and New Zealand point to the need for further international investigations.
authors.affiliation: Faculty of Social and Human Sciences, School of Psychology, University of Southampton, Southampton, United Kingdom.
authors.forename: Conal
authors.initials: C
authors.lastname: Twomey
authors.affiliation: Health Service and Population Research Department, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.
authors.forename: A Matthew
authors.initials: AM
authors.lastname: Prina
authors.affiliation: Faculty of Medicine, University of Southampton, Southampton, United Kingdom.
authors.forename: David S
authors.initials: DS
authors.lastname: Baldwin
authors.affiliation: Health Service and Population Research Department, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.
authors.forename: Jayati
authors.initials: J
authors.lastname: Das-Munshi
authors.affiliation: Faculty of Medicine, University of Southampton, Southampton, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Kingdon
authors.affiliation: Health Service and Population Research Department, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Koeser
authors.affiliation: Health Service and Population Research Department, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Prince
authors.affiliation: Health Service and Population Research Department, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Stewart
authors.affiliation: Health Service and Population Research Department, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.
authors.forename: Alex D
authors.initials: AD
authors.lastname: Tulloch
authors.affiliation: Faculty of Social and Human Sciences, School of Psychology, University of Southampton, Southampton, United Kingdom.|Research Unit for Biopsychosocial Health, Department of Medical Informatics, Biometry and Epidemiology-IBE, Ludwig-Maximilians-University (LMU), Munich, Germany.|Swiss Paraplegic Research (SPF), Nottwil, Switzerland.
authors.forename: Alarcos
authors.initials: A
authors.lastname: Cieza
mesh_terms: D015331:Cohort Studies; D003365:Costs and Cost Analysis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008603:Mental Health; D008605:Mental Health Services / Q000191:economics*; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data*