Objective: The main goal of our study was to examine factor structure of schizophrenia and bipolar affective disorder in the Wielkopolska population, using dimension reduction techniques.
Methods: Schizophrenia (n=443) and bipolar affective disorder (n=499) patients were assessed using Operational Criteria Checklist (OPCRIT). Principal component analysis and Maximum Likelihood Factor analysis were carried out to obtain factor structure with significance level for the factor loadings exceeding 0.4. Varimax and promax rotations were used to identify the meaningful factors.
Results: Rotated solution indicated multidimensional structure for depression and excitement as well as positive domains in the schizophrenia sample. Negative and disorganized dimensions existed as single factors, with item composition similar to that already described. Additionally, a new "social functioning" dimension was identified. In bipolar affective disorder sample, the interpretable dimensions included: depression, psychotic, atypical depression, negative, substance use, excitement and "social functioning". Factor structure of the combined sample consisted of depression, excitement, disorganization, delusions, substance use, negative and social functioning factors.
Conclusions: Our results indicated multidimensional and hierarchical structures for some of the previously described dimensions. Additional use of items not exactly related to disease symptoms lead to discovery of "substance use" and "social functioning" dimensions.
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