Psychometric properties of the abbreviated version of the Scale to Assess Unawareness in Mental Disorder in schizophrenia
BACKGROUND
The Scale to Assess Unawareness in Mental Disorder (SUMD) is widely used in clinical trials and epidemiological studies but more rarely in clinical practice because of its length (74 items). In clinical practice, it is necessary to provide shorter instruments. The aim of this study was to investigate the validity and reliability of the abbreviated version of the SUMD.


METHODS



DESIGN
We used data from four cross-sectional studies conducted in several psychiatric hospitals in France.


INCLUSION CRITERIA
a diagnosis of schizophrenia based on DSM-IV criteria.


DATA COLLECTION
socio-demographic and clinical data (including duration of illness, Positive and Negative Syndrome Scale, and the Calgary Depression Scale); quality of life; SUMD.


STATISTICAL ANALYSIS
confirmatory factor analyses, item-dimension correlations, Cronbach's alpha coefficients, Rasch statistics, relationships between the SUMD and other parameters. We tested two different scoring models and considered the response 'not applicable' as '0' or as missing data.


RESULTS
Five hundred and thirty-one patients participated in this study. The 3-factor structure of the SUMD (awareness of the disease, consequences and need for treatment; awareness of positive symptoms; and awareness of negative symptoms) was confirmed using LISREL confirmatory factor analysis for the two models. Internal item consistency and reliability were satisfactory for all dimensions. External validity testing revealed that dimension scores correlated significantly with all PANSS scores, especially with the G12 item (lack of judgement and awareness). Significant associations with age, disease duration, education level, and living arrangements showed good discriminant validity.


CONCLUSION
The abbreviated version of the SUMD appears to be a valid and reliable instrument for measuring insight in patients with schizophrenia and may be used by clinicians to accurately assess insight in clinical settings.