Comparison of self-report and performance-based measures of everyday functioning in individuals with schizophrenia: implications for measure selection

Introduction. Both self-report and performance-based measures are often used in assessment of everyday functioning for individuals with schizophrenia. However, there is little evidence of overlap between them, and there are no established standards for which measures might be most appropriate. In order to better understand differences among these types of measures, we examined relationships between a self-report and two performance-based measures of everyday functioning. We also examined their patterns of interrelationships to neurocognition and psychiatric symptoms. Methods. Participants were 71 outpatients with schizophrenia spectrum disorder. Measures of everyday functioning (Independent Living Skill Survey-Self Report (ILSS-SR); University of California San Diego Performance-based Skills Assessment; and Medication Management Ability Assessment), cognition and psychiatric symptoms were administered. Correlation analyses were conducted to examine the relationships among the functioning measures, and their relationships to cognition and symptoms. Regression analyses further examined the unique contributions of neurocognitive and symptom variables to functional measures. Results. Consistent with the literature, the two performance-based measures were related to each other, but not to the self-report measure. Whereas the performance-based measures were related to neurocognition but not to the psychiatric symptoms, the opposite pattern was observed for the self-report measure. Conclusions. The pattern of interrelationships among these self-report and performance-based measures suggests that they tap different aspects of everyday functioning. This has important implications for measure selection, particularly for evaluating intervention outcomes. When targeting symptoms, a self-report measure like the ILSS-SR may be more appropriate, whereas a performance-based measure may be more sensitive to functional changes subsequent to treatments targeting cognition.