Validation of the Scale of Functioning in Older Outpatients With Schizophrenia

The authors investigated the reliability and validity of the Scale of Functioning (SOF), a 15-item scale, in 78 middle-aged and elderly outpatients with schizophrenia. The SOF score had both high internal consistency and high interrater reliability and significantly discriminated between these patients and 45 normal comparison subjects. SOF scores correlated significantly with scores on several psychopathology rating scales as well as a number of existing instruments assessing cognitive or functional ability. Principal-components analysis using different scales of functional ability, psychopathology, and global cognitive performance and treated by orthogonal rotation revealed two domains of functioning, one of which was defined by the SOF along with scales for activities of daily living, negative symptoms, and cognitive impairment. The other domain was defined by scales for quality of well-being, social adjustment, and positive and depressive symptoms. Results support the construct validity of the SOF in late-life schizophrenia.