The prodromal questionnaire (PQ): preliminary validation of a self-report screening measure for prodromal and psychotic syndromes

Schizophr Res. 2005 Nov 1;79(1):117-25.


This study aims to establish preliminary validity of the Prodromal Questionnaire (PQ), a 92-item self-report screening measure for prodromal and psychotic symptoms. Adolescents and young adults (N = 113) referred to a prodromal psychosis research clinic completed the PQ and the Structured Interview for Prodromal Syndromes (SIPS [Miller, T.J., McGlashan, T.H., Woods, S.W., Stein, K., Driesen, N., Corcoran, C.M., Hoffman, R., Davidson, L., 1999. Symptom assessment in schizophrenic prodromal states. Psychiatric Quarterly 70(4), 273-287]), an interview with established validity for predicting future psychosis. When maximizing selection of true positive cases, scores on a subset of PQ items that assess positive symptoms predicted a concurrent prodromal or psychotic SIPS diagnosis with 90% sensitivity and 49% specificity. The PQ shows good preliminary validity in detecting individuals with an interview-diagnosed prodromal or psychotic syndrome, but it is less sensitive to the threshold between prodromal and full-blown psychosis.

Publication types

  • Validation Study

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Female
  • Humans
  • Male
  • Mass Screening / methods*
  • Observer Variation
  • Prevalence
  • Psychotic Disorders / diagnosis*
  • Psychotic Disorders / epidemiology*
  • ROC Curve
  • Reproducibility of Results
  • Surveys and Questionnaires*