[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.

Aim: 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.

Method: 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.

Conclusion: 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.