Assessing self-reported clinical high risk symptoms: The psychometric properties of the polish version of the prodromal questionnaire-brief and a proposal for an alternative approach to scoring.

Abstract

Psychotic-like experiences (PLEs) might occur in the general population as low-risk individual differences or prodromal features, requiring quick detection and early intervention. The aims of this study were to conduct a mini-systematic review of the prognostic abilities of the Prodromal Questionnaire-Brief (PQ-B), describe the PLEs distribution for the first time in a Polish population, assess PQ-B reliability and propose an innovative scoring approach based on cluster analysis. Five hundred and twenty eight (334 female) adult volunteers underwent screening with the PQ-B, 49% also underwent the early psychosis screening test PRIME, to verify the tests' psychometric properties, to compare the prognostic accuracy of the PQ-B to the more restrictive PRIME, and to the detected types of possible diagnosis in the general population. Almost 70% of respondents met the prognostic criteria of the PQ-B while only 30.6% met the PRIME criteria. Both tests proved reliable (α > .835) and valid (rho >.710; P < .001). A cluster analysis identified three different sub-groups detected with the PQ-B: healthy individuals without PLE; healthy with low-distressing PLEs; and possibly prodromal subjects reporting less frequent but more distressing PLEs and no worries about their own mental state. Also in systematic reviews, authors of different adaptations have observed that the PQ-B has too low specificity and postulated the need for higher cut-offs. Study provides evidence of good reliability and sensitivity of the PQ-B in assessing PLEs among the general population, but emphasizes that straightforward quantitative scoring criteria are still unclear. A more qualitative approach might be useful for differentiating true prodromal subjects from clinically low-risk individual differences.