The Schizophrenia Proneness Instrument, Child and Youth version (SPI-CY): practicability and discriminative validity

Background: Basic symptom (BS) criteria have been suggested to complement ultra-high risk (UHR) criteria in the early detection of psychosis in adults and in children and adolescents. To account for potential developmental particularities and a different clustering of BS in children and adolescents, the Schizophrenia Proneness Instrument, Child and Youth version (SPI-CY) was developed.

Aims: The SPI-CY was evaluated for its practicability and discriminative validity.

Method: The SPI-CY was administered to 3 groups of children and adolescents (mean age 16; range = 8-18; 61% male): 23 at-risk patients meeting UHR and/or BS criteria (AtRisk), 22 clinical controls (CC), and 19 children and adolescents from the general population (GPS) matched to AtRisk in age, gender, and education. We expected AtRisk to score highest on the SPI-CY, and GPS lowest.

Results: The groups differed significantly on all 4 SPI-CY subscales. Pairwise post-hoc comparisons confirmed our expectations for all subscales and, at least on a descriptive level, most items. Pairwise subscale differences indicated at least moderate group effects (r ≥ 0.37) which were largest for Adynamia (0.52 ≤ r ≥ 0.70). Adynamia also performed excellent to outstanding in ROC analyses (0.813 ≤ AUC ≥ 0.981).

Conclusion: The SPI-CY could be a helpful tool for detecting and assessing BS in the psychosis spectrum in children and adolescents, by whom it was well received. Furthermore, its subscales possess good discriminative validity. However, these results require validation in a larger sample, and the psychosis-predictive ability of the subscales in different age groups, especially the role of Adynamia, will have to be explored in longitudinal studies.