title: Evaluating cutpoints for the MHI-5 and MCS using the GHQ-12: a comparison of five different methods.
abstract: BACKGROUND
  The Mental Health Inventory (MHI-5) and the Mental Health Component Summary score (MCS) derived from the Short Form 36 (SF-36) instrument are well validated and reliable scales. A drawback of their construction is that neither has a clinically validated cutpoint to define a case of common mental disorder (CMD). This paper aims to produce cutpoints for the MHI-5 and MCS by comparison with the General Health Questionnaire (GHQ-12).
  
  
  METHODS
  Data were analysed from wave 9 of the British Household Panel Survey (2000), providing a sample size of 14,669 individuals. Receiver Operating Characteristic (ROC) curves were used to compare the scales and define cutpoints for the MHI-5 and MCS, using the following optimisation criteria: the Youden Index, the point closest to (0,1) on the ROC curve, minimising the misclassification rate, the minimax method, and prevalence matching.
  
  
  RESULTS
  For the MHI-5, the Youden Index and the (0,1) methods both gave a cutpoint of 76, minimising the misclassification rate gave a cutpoint of 60 and the minimax method and prevalence matching gave a cutpoint of 68. For the MCS, the Youden Index and the (0,1) methods gave cutpoints of 51.7 and 52.1 respectively, minimising the error rate gave a cutpoint of 44.8 and both the minimax method and prevalence matching gave a cutpoint of 48.9. The correlation between the MHI-5 and the MCS was 0.88.
  
  
  CONCLUSIONS
  The Youden Index and (0,1) methods are most suitable for determining a cutpoint for the MHI-5, since they are least dependent on population prevalence. The choice of method is dependent on the intended application. The MHI-5 performs remarkably well against the longer MCS.
authors.affiliation: Dept. of Primary Care and Public Health, Centre for Health Sciences Research, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4YS, UK. kellymj1@cf.ac.uk
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Kelly
authors.forename: Frank D
authors.initials: FD
authors.lastname: Dunstan
authors.forename: Keith
authors.initials: K
authors.lastname: Lloyd
authors.forename: David L
authors.initials: DL
authors.lastname: Fone
mesh_terms: D001008:Anxiety Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D017281:Cost of Illness; D003627:Data Interpretation, Statistical; D003866:Depressive Disorder / Q000175:diagnosis* / Q000453:epidemiology*; D005190:Family / Q000523:psychology*; D006304:Health Status; D006801:Humans; D008960:Models, Psychological; D011634:Public Health; D012372:ROC Curve; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires