Investigating subjective cognitive complaints in psychosis: Introducing the brief scale to Investigate cognition in schizophrenia (SSTICS-Brief)

Background: Cognitive difficulties are a core deficit for people with schizophrenia and are generally assessed with neuropsychological tests. Self-report assessments are also useful in understanding difficulties from the service user’s perspective. This study aims to introduce and test the shorter version of the Subjective Scale to Investigate Cognition in Schizophrenia (SSTICS) to improve its acceptability and comprehensibility. Methods: In consultation with service users and clinicians, we identified items from the original 21-item SSTICS that were found difficult and these were excluded. The reduced scale was explored with Confirmatory Factor Analysis (CFA) in two independent samples in the UK and Canada. Convergent validity with symptoms and IQ was assessed and compared between the original and the reduced scale. Results: Six-hundred and seven people with schizophrenia and first-episode psychosis took part in this study. Seven items were removed to produce the SSTICS-Brief. This had good reliability and the CFA confirmed a unidimensional structure. Convergent validity with symptoms and IQ were optimal between the long and short versions. Conclusions: The SSTICS-B has better acceptability than its longer form and could be administered in less time. The resulting measure is likely to be a valuable short self-assessment of cognitive complaints for people with schizophrenia.