Reliability and validity study of schizophrenia cognition rating scale (SCORS) which assess cognitive impairment in schizophrenia patients

Objective: Neurocognitive impairments in schizophrenia are significant important aspects of the disease even though they are not evident in diagnostic criteria. Neurocognitive impairments defines skills which directly effect daily life functioning of patients such as memory, attention, executive functions, language skills. The aim of this study was to demonstrate validity and reliability of Turkish form of "Schizophrenia Cognition Rating Scale" in schizophrenia patients, which has been developed by Richard Keefe et al. Material and Method: Our sample consisted of a total of 170 volunteers, including 130 schizophrenia patients who met DSM-V criteria for schizophrenia and 40 healthy controls. Sociodemographic data form, schizophrenia cognition rating scale, Positive and Negative Syndrome Scale (PANSS) and REY verbal learning and memory test, Trial Making, Stroop test, Digit Symbol, Digit Span test, Verbal Fluency test, Animal Naming test, Wisconsin Card Sorting test were administered to patients with schizophrenia. Sociodemographic data form and Structured Clinical Interview for DSM-V (SCID) were performed for healthy controls. For assessing the reliability of this new scale, internal consistency, test-retest and interrater reliability analyses were conducted. The validity of the scale was assessed with similar scale validity, factor analysis and differential validity methods. Results: We found clear evidence about reliability and validity of SCoRS in our study. Conducted factor analysis shows SCoRS is structured with 4 factors (memory, attention/vigilanse, executive functions, psicomotor activation subscales) which defined %63,4 of overall variance and has an acceptable internal consistency ( for patient form r=0.937, for informant r=0.940, for interviewer form r=0.937). We also determined high interrater reliability (patient form r=0.90, informant r=0.95, for interviewer form r=0.98), high test-retest reliability (patient form r=0.990, informant r=0.977and interviewer form r=0.976) and high differentiation capacity between patients and healthy volunteers (p<0.001). We found out at similar scale validity, SCoRS shows moderate significant correlation with REY test (late recall) in patient, informant and interviewer subscales (r:-0,48); mildly significant correlation with Trail making A and Trail Making B tests in patient, informant and interviewer subscales; moderate significant correlation with Trail Making B test in global assessment score (r:-0.36); moderate significant correlation with Verbal Fluency test in all of four subscales (r:-0,46); moderate significant correlation with number of categories subtest of Wisconsin Card Sorting test (r:-0,38) and lastly moderate significant correlation with correct percentage of Wisconsin Card Sorting test in Global Assessment Score (r:-0,34) Conclusion: Schizophrenia Cognition Rating Scale that contributed in Turkish with this study has demonstrated standardized rating properties in our study. Schizophrenia cognition rating scale would contribute to determine severity of neurocognitive impairments evident in schizophrenia patients, trace progression of cognitive impairments in clinical follow-ups and clinical studies. Key Words: Schizophrenia, neurocognitive impairments, Schizophrenia Cognitive Rating Scale