Objective: Traditional measures for assessing functioning with adult patients with schizophrenia have been shown to be insufficient for assessing the issues that occur in adolescents and young adults at clinical high risk (CHR) for psychosis. The current study provides an expanded validation of the Global Functioning: Social (GF:Social) and Role (GF:Role) scales developed specifically for use with CHR individuals and explores the reliability and accuracy of the ratings, the validity of the scores in comparison to other established clinical measures, stability of functioning over a 2-year period, and psychosis predictive ability.
Methods: Seven hundred fifty-five CHR individuals and 277 healthy control (HC) participants completed the GF:Social and Role scales at baseline as part of the North American Prodrome Longitudinal Study (NAPLS2).
Results: Inter-rater reliability and accuracy were high for both scales. Correlations between the GF scores and other established clinical measures demonstrated acceptable convergent and discriminant validity. In addition, GF:Social and Role scores were unrelated to positive symptoms. CHR participants showed large impairments in social and role functioning over 2-years, relative to the HCs, even after adjusting for age, IQ, and attenuated positive symptoms. Finally, social decline prior to baseline was more pronounced in CHR converters, relative to non-converters.
Conclusions: The GF scales can be administered in a large-scale multi-site study with excellent inter-rater reliability and accuracy. CHR individuals showed social and role functioning impairments over time that were not confounded by positive symptom severity levels. The results of this study demonstrate that social decline is a particularly effective predictor of conversion outcome.
Keywords: Adolescent; CHR; Global Functioning: Role; Global Functioning: Social; NAPLS; Prodromal; scale validation.
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