[Schizophrenia Cognition Rating Scale Japanese version (SCoRS-J) as a co-primary measure assessing cognitive function in schizophrenia].

The assessment of cognitive function is important for patients with schizophrenia because cognitive impairment is a core feature of the disease, and is a major determinant of functional outcome. To implement a practical assessment tool, we previously developed the Japanese-language version of the Brief Assessment of Cognition in Schizophrenia that objectively measures cognitive domains relevant to outcome. Meanwhile, the U.S. Food and Drug Administration took the position that a drug to improve coghition should show changes on an additional measure (a co-primary), in addition to an accepted consensus cognitive performance measure that is considered functionally meaningful. Thus, four potential co-primary measures, two measures of functional capacity and two interview-based measures of cognition, were evaluated for psychometric properties and validity. The Schizophrenia Cognition Rating Scale (SCoRS) is one of the interview-based measures of cognition. It consists of 20 questions to measure attention, memory, reasoning and problem solving, working memory, language production, and motor skills, which are related to day-to-day functioning. University of California at San Diego Performance-Based Skills Assessment (UPSA) is one of the measures of functional capacity. For its clinical application, we developed the Japanese-language version of the SCoRS (SCoRS-J) and UPSA (UPSA-J) through back-translation into English.