Psychosis Risk: Time to Look Empirically at a First-step Economical-pragmatic Way to Examine Anomalous Self-experience. Exploring the SQuEASE-11.

Background: Since the late 1990s, there has been a worldwide surge of scientific interest in the pre-psychotic phase, resulting in the introduction of several clinical tools for early detection. The predictive accuracy of these tools has been limited, motivating the need for methodological and perspectival improvements. The EASE manual supports systematic assessment of anomalous self-experience, and proposes an overall model of understanding how most psychotic experiences may be initially generated on the basis of a unifying, fundamental, pre-reflective distortion of subjectivity.

Study design: The EASE is time-consuming, so in order to spread the use of this essential perspective of psychosis risk we selected prototypical and frequent phenomena from the EASE, combining them into SQuEASE-11. To investigate this instrument for clinical relevance, basic psychometric properties, factor structure, and relationships with gold standard instruments and the full EASE, it was administered as an interview in the STEP intervention trial (Melbourne, Australia), with 328 clinical high-risk for psychosis (CHR-P) patients.

Study results: The SQuEASE-11 had moderate internal consistency and revealed two correlated factors. Significant relationships were observed between the SQuEASE-11 and the widely used and validated instruments CAARMS, BPRS, SANS, MADRS, DACOBS, and SOFAS. The correlation with the full EASE was very strong.

Conclusions: These 11 items do not necessarily relate specifically to ipseity disturbance, but the SQuEASE-11 seems to be a clinically relevant and brief supplementary first-line interview in CHR-P subjects. It may give a qualified indication of the need for a complete EASE interview, and it may also, importantly, inform treatment planning.