The Korean Version of the Schizophrenia Cognition Rating Scale: Reliability and Validity

OBJECTIVE This study's aim was to develop and standardize a Korean version (SCoRS-K) of the Schizophrenia Cognition Rating Scale (SCoRS), which is used to evaluate the degree of cognitive dysfunction affecting the everyday functioning of people with schizophrenia. METHODS Eighty-four schizophrenia patients with stable symptoms who were receiving outpatient treatment and rehabilitation therapy, and 29 demographically matched non-patient controls, participated in the study. Demographic data were collected, and clinical symptoms, cognitive function, and social function were evaluated to verify SCoRS-K's reliability and validity. Clinical symptoms were evaluated using the Positive and Negative Syndrome Scale and the Clinical Global Impression-Schizophrenia Scale. Cognitive function was evaluated using a short form of the Korean Wechsler Adult Intelligence Scale and the Wisconsin Card Sorting Test (WCST). Social function was evaluated using the Social and Occupational Functioning Assessment Scale, the Schizophrenia Quality of Life Scale, and the Social Functioning Scale. RESULTS Data analysis demonstrated SCoRS-K's statistically significant reliability and validity. SCoRS-K has high internal consistency (Cronbach's alpha; patient 0.941, informant 0.905, interviewer 0.964); test-retest reliability [patient 0.428 (p=0.003), informant 0.502 (p<0.001), interviewer 0.602 (p<0.001); and global rating 0.642 (p<0.001)]. The mean scores of subjects were significantly higher than those of the controls (p<0.001), demonstrating SCoRS-K's discriminant validity. Significant correlations between the total scores and global rating score of SCoRS-K and those of the scales and tests listed above (except WCST) support SCoRS-K's concurrent validity. CONCLUSION SCoRS-K is a useful instrument for evaluating the degree of cognitive dysfunction in Korean schizophrenia patients.