The 68 symptoms of the clinical high risk for psychosis: Low similarity among fourteen screening questionnaires

The Clinical High Risk for psychosis (CHR) is a heterogeneous condition with multiple symptoms. CHR screening is challenging in routine care, as a wide variety of questionnaires exists. We propose to explore the extent to which these questionnaires differ or overlap in item content. We performed a systematic and quantitative analysis of item content in a set of widely-used CHR screening questionnaires. Items were extracted from questionnaires and reworded according to the Structured Interview for Psychosis-Risk Syndromes (SIPS). Then, symptoms were generated from individual items. The Jaccard Index was calculated to assess content overlap. The 14 analysed questionnaires were composed of 347 items, from which 198 symptoms were generated and, in turn, collapsed into 68 distinct symptoms. Positive symptoms were the most commonly represented. The overall overlap across questionnaires showed weak similarity (Jaccard = 0.19±0.50). CHR screening questionnaires might evaluate the same broad clinical construct, but have different scopes within that construct, and may be more or less comprehensive than one another. Clinicians and researchers should be mindful of the specific features of each instrument for optimal CHR screening.