Assessing self-reported clinical high risk symptoms in community-derived adolescents: A psychometric evaluation of the Prodromal Questionnaire-Brief.

ABSTRACT

BACKGROUND: The reliable early identification of individuals at risk for psychosis requires well-validated screening measures. To date, there is little information about the psychometric properties of the screening measures for psychosis risk in nonclinical adolescents. The main purpose of the present study was to validate the Prodromal Questionnaire-Brief (PQ-B) in a community sample of non-clinical Spanish adolescents. We also analyzed the prevalence, factorial validity, and reliability of the PQ-B scores as well as the relationship between self-reported clinical high risk symptoms and schizotypal traits. METHOD: Four hundred and forty-nine high-school students participated in a cross-sectional survey. The PQ-B and the Oviedo Schizotypy Assessment Questionnaire (ESQUIZO-Q) were used. RESULTS: Although 85.1% of the total sample reported at least one clinical high risk symptom, only 16% of the adolescents scored above the standardized cut-off. The PQ-B revealed an essentially unidimensional structure. The internal consistency of the PQ-B total score was 0.93. Pearson correlation coefficients indicated a high degree of overlap between self-reported clinical high risk symptoms and Positive and Disorganized schizotypal traits. A Canonical correlation between the PQ-B total score and ESQUIZO-Q dimensions showed that the associated variance between both sets of variables was 45.4% (adjusted R(2)=0.45). CONCLUSIONS: The PQ-B is a brief, easy, and reliable tool for screening self-reported clinical high risk symptoms in adolescents from the general population. These results also indicated that self-reported clinical high risk symptoms and schizotypal traits are closely associated at the subclinical level. The assessment of psychosis risk symptoms and their relationship with other distal risk factors, in a close-in strategy, may enhance the early identification of individuals at heightened risk for psychosis spectrum disorders.