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

• Published in: PloS one Vol. 11; no. 11; p. e0167103
• Main Authors: Twomey, Conal, Prina, A Matthew, Baldwin, David S, Das-Munshi, Jayati, Kingdon, David, Koeser, Leonardo, Prince, Martin J, Stewart, Robert, Tulloch, Alex D, Cieza, Alarcos
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 30-11-2016; Public Library of Science (PLoS)
• Subjects: Biology and Life Sciences; Clusters; Cohort analysis; Cohort Studies; Cost analysis; Cost benefit analysis; Costs; Costs and Cost Analysis; Economic aspects; Epidemiology; Female; Follow-Up Studies; Forecasts and trends; Health care; Health care costs; Health care expenditures; Health problems; Health services; Hospitals; Humans; Injury prevention; Male; Management; Medicine; Medicine and Health Sciences; Mental disorders; Mental Health; Mental health care; Mental health services; Mental Health Services - economics; Neurosciences; Outcome Assessment, Health Care - statistics & numerical data; Patients; Payment systems; Population; Psychiatry; Psychology; Psychosis; Self-injury; Social Sciences; Studies; Systematic review; United Kingdom > UK; England
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0167103

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.
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.
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.
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.