title: [The detection of people with an ultra-high risk of developing psychosis: detection methods and baseline characteristics of the population].
abstract: BACKGROUND
  It has proved possible to detect persons who are in an at risk mental state (arms) and who run the risk of developing a psychosis. We need to find out whether the detection can be successfully carried out when these patients are being cared for by the secondary mental health care services.
  
  
  OBJECTIVE
  To summarise three studies forming part of a Ph.D. thesis about persons with a high risk of developing psychosis and to explore whether a two-stage screening programme can detect arms-patients among a general help-seeking population.
  
  
  METHODS
  The case register of Parnassia (in The Hague) was used to pick out all persons who had developed a first-episode psychosis between 2005 and 2009 and who had sought help for non-psychotic psychological problems during this phase preceding a first-episode psychosis. Data from the Dutch edie-nl study were used to find out whether a two-stage screening method was able to detect arms-patients (aged 18-30) more accurately than the traditional screening method. The two-stage screening consisted of a Prodromal Questionnaire relating to all help-seeking subjects in the general population, followed by a gold-standard interview with patients who achieved a score higher than the cut-off level.
  
  
  RESULTS
  56.2% of the first-episode psychotic patients received help for non-psychotic psychiatric problems in the secondary mental health care services. Screening detected more arms-patients than did the referral method and the 'referred' patients developed three times as many psychotic symptoms over a period of 18 months.
  
  
  CONCLUSIONS
  The secondary mental health care services care for 4% of the arms-patients and are in a position to detect arms-patients provided they use two-stage screening. Screening leads to fewer false-negative results than does the 'referral' method.
authors.forename: J
authors.initials: J
authors.lastname: Rietdijk
authors.forename: M
authors.initials: M
authors.lastname: van der Gaag
mesh_terms: D000293:Adolescent; D000328:Adult; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics / Q000592:standards*; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000453:epidemiology; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult