Symptom structure in obsessive-compulsive disorder: a confirmatory factor-analytic study
Section snippets
Participants
Participants were 203 individuals diagnosed with OCD at the Anxiety Disorders Clinic of the Clarke Institute of Psychiatry. Of these, 87 (43%) were diagnosed according to DSM-III-R criteria and 116 (57%) were diagnosed according to DSM-IV criteria. All subjects were diagnosed by clinical interview with an experienced psychiatrist specializing in anxiety disorders. For those individuals meeting DSM-IV criteria, diagnoses were confirmed using the Structured Clinical Interview for DSM-IV (SCID-
Model 1 (single-factor)
The goodness of fit indices shown in Table 1 indicate that the unidimensional, single- factor model did not provide a good fit for the data in the second-order analysis. The χ2 value for the single-factor model was statistically significant, and none of the remaining indices approached criterion values. In view of this, we did not perform an item-level analysis.
Model 2 (two-factor)
As presented in Table 1, the goodness of fit indices show that the two-factor model did not provide adequate fit for the category level
Discussion
This study examined four potential models of symptom structure in OCD: a single-factor model, a two-factor model, and two multidimensional models, specifying three and four factors. A confirmatory factor analytic approach was used to determine which of these best explained the symptom data obtained in a large sample of individuals with OCD. Satisfactory support was found only for the multidimensional model proposed by Leckman et al. (1997), comprising four factors related to obsessions and
Acknowledgements
Laura J. Summerfeldt acknowledges the support provided by a Doctoral Fellowship from the Social Sciences and Humanities Research Council of Canada (SSHRC). The authors are grateful to Dr James D.A. Parker for his statistical advice and to Veronika Huta for her help with the data collection.
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