Cognitive deficits are associated with disability in people with schizophrenia so treatment of cognitive impairment has been proposed as an intervention to reduce disability. However, studies relying on patient self-report have found very minimal relationships between ratings of real-world functioning and cognitive performance, raising questions about the measurement of real-world functioning as a treatment outcome. The Validation of Everyday Real-world Outcomes (VALERO) study was conducted to evaluate functional rating scales and to identify the rating scale or scales most robustly related to performance-based measures of cognition and everyday living skills.
198 adults with schizophrenia were tested with the neurocognitive measures from the MATRICS Consensus cognitive Battery and performed the UCSD performance-based skills assessment-Brief and advanced finances subtest from the Everyday Functioning Battery. They and a friend, relative, clinician, or case manager also reported their everyday functioning on 6 ratings scales: Social Behavior Schedule, Social Adjustment Scale, Heinrichs Carpenter Quality of Life Scale, Specific Levels of Functioning, Independent Living skills Survey, and Life Skills Profile. Best judgment ratings were generated by an interviewer who administered the rating scales to patients and informants.
Statistical analyses developed an ability latent trait that reflected scores on the three performance-based (i.e., ability) measures and canonical correlation analysis related interviewer ratings to the latent trait. The overall fit of the model with all six rating scales was good: χ2 = 78.100, df = 56, p = .027, and RMSEA = .078. Individual rating scales that did not improve the fit of the model were systematically deleted and a final model with two rating scales fit the data: χ2 = 32.059, df = 24, p = .126, RMSEA = .072. A regression analysis found that the Specific Levels of Functioning was a superior predictor of the three-performance based ability measures.
We found that systematic assessments of real world functioning are related to performance on neurocognitive and functional capacity measures. Of the six rating scales evaluated, the Specific Levels of Functioning (SLOF) was best in this study. Use of a single rating scale provides a very efficient assessment of real-world functioning that accounts for considerable variance in performance-based scores.