Objective: To obtain Food and Drug Administration approval for the treatment of cognitive impairments associated with schizophrenia, a drug will need to demonstrate benefits beyond those that may be documented on objective cognitive tests. Interview-based measures of cognition such as the Cognitive Assessment Interview (CAI) are candidate coprimary outcome measures.
Methods: Psychiatrically stable schizophrenia outpatients (n=150) were studied using the CAI to obtain information about cognitive functioning from both the patient and an informant. Patients also received objective assessments of neurocognition, functional capacity, functional outcome, and symptoms, at baseline and 1 month later.
Results: The CAI had good internal consistency (Cronbach's alpha=.92) and good test-retest reliability (r=.83). The CAI was moderately correlated with objective neurocognitive test scores (r's=-.39 to -.41) and moderately correlated with social functioning (r=-.38), work functioning (r=-.48), and overall functional outcome (r=-.49). The correlations of CAI scores with external validity indicators did not differ significantly by source of information (patient alone ratings were valid). Overall functional outcome correlated more strongly with patient CAI scores (r=-.50) than with objective neurocognitive test scores (r=.29) or functional capacity (r=.29).
Conclusions: Field testing of the CAI produced reliable ratings of cognitive functioning that were correlated with functional outcome. Patient ratings alone yielded scores with reliability and validity values appropriate for use in clinical trials. The CAI appears to provide useful complementary information and possesses practical advantages for rating cognitive functioning including an interview-based method of administration, brief assessment time (15 min for the patient assessment), little or no practice effects, and ease of scoring.