MedWire News: A brief version of the Prodromal Questionnaire (PQ-B) is effective for identifying patients with prodromal psychosis syndromes, researchers have found.
"A growing body of research has demonstrated that individuals at ultra-high-risk (UHR) for psychosis can be reliably diagnosed using clinical interviews such as the Structured Interview for Prodromal Syndromes (SIPS) and the Comprehensive Assessment of At-Risk Mental States," explain Rachel Loewy (University of California at San Francisco, USA) and team.
However, they add: "Although these interviews are indispensable in diagnosing prodromal psychosis, clinicians need specialized training to use them and they take several hours of clinicians' and patients' time."
The researchers therefore investigated the validity of the self-report PQ-B for identifying patients with psychosis risk syndromes. This was developed from the original 92-item Prodromal Questionnaire and includes 18 positive symptom, social functioning, and academic/occupational functioning items. Following each individual item, two follow-up questions were asked about frequency and related distress or impairment.
In total, 141 adolescents and young adults who presented for clinical assessment at one of two early psychosis research clinics completed the PQ-B and underwent SIPS assessment.
After SIPS assessment, 44% of patients were diagnosed with a prodromal syndrome, 42% were diagnosed as being fully psychotic, and 13% received no psychotic spectrum diagnosis.
The researchers found that endorsement of three or more positive symptoms on the PQ-B differentiated between patients with a prodromal syndrome or full psychosis and those without a psychotic spectrum diagnosis with a sensitivity of 89%, a specificity of 58%, and a positive likelihood ratio of 2.12.
A distress score cutoff of six or more associated with endorsed positive symptoms increased the specificity to 68%, while retaining a similar sensitivity of 88%.
The PQ-B remained effective when participants with full psychosis were excluded from the analyses.
Loewy and team conclude in the journal Schizophrenia Research: "These results suggest that the PQ-B may be used as an effective, efficient self-report screen for prodromal psychosis syndromes when followed by diagnostic interview, in a two-stage evaluation process in help-seeking populations."
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