Symptom structure in obsessive-compulsive disorder: a confirmatory factor-analytic study

https://doi.org/10.1016/S0005-7967(98)00134-XGet rights and content

Abstract

Although obsessive-compulsive disorder (OCD) has long been a unitary diagnosis, there is much recent interest in its potential heterogeneity, as manifested by symptom subgroups. This study evaluated existing models of symptom structure in a sample of 203 individuals with OCD. Using confirmatory factor analysis, we examined the ability of each model to account for two levels of data: a priori symptom groupings (second-order) and individual symptoms, identified by the Yale–Brown Obsessive Compulsive Scale symptom checklist. Four models were examined: a single-factor, a two-factor (i.e., obsessions and compulsions), and two multidimensional models, comprising three and four factors. Adequate fit was found solely for the four-factor model—specifying obsessions/checking, symmetry/ordering, contamination/cleaning, and hoarding—but only at the second-order level; it did not account for relationships among discrete symptoms. Parameter estimates showed within-factor heterogeneity, as well as overlap between factors, most notably the two representing checking and contamination-related symptoms. The implications of these findings are discussed. Results provide evidence for the multidimensionality of OCD symptoms, but suggest that a comprehensive model has yet to be identified. They also point to the inadequacy of groupings based solely upon overt behavioural similarities (e.g., ‘checking’). Recommendations are made for future research.

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.

References (49)

  • P. Van Oppen et al.

    The structure of obsessive-compulsive symptoms

    Behaviour Research and Therapy

    (1995)
  • N. Amir et al.

    Factor structure of the Yale-Brown Obsessive Compulsive Scale

    Psychological Assessment

    (1997)
  • American Psychiatric Association (1952). Diagnostic and statistical manual of mental disorders. Washington, DC:...
  • American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders (4th edn.). Washington,...
  • J.C. Anderson et al.

    The effect of sampling error on convergence, improper solutions, and goodness-of-fit indices for maximum likelihood confirmatory factory analysis

    Psychometrika

    (1984)
  • L. Baer

    Factor anaysis of symptom subtypes of obsessive compulsive disorder and their relation to personality and tic disorders

    Journal of Clinical Psychiatry

    (1994)
  • P.M. Bentler

    Comparative fit indices in structural models

    Psychological Bulletin

    (1990)
  • Bentler...
  • D.A. Cole

    Utility of confirmatory factor analysis in test validation research

    Journal of Consulting and Clinical Psychology

    (1987)
  • J.L. Eisen et al.

    Obsessive compulsive disorder with psychotic features

    Journal of Clinical Psychiatry

    (1993)
  • W. Fals-Stewart

    A dimensional analysis of the Yale–Brown Obsessive Compulsive Scale

    Psychological Reports

    (1992)
  • First, M. B., Spitzer, R. L., Gibbon, M., & Williams, J. B. W. (1996). Structured Clinical Interview for DSM-IV—Patient...
  • F.J. Floyd et al.

    Factor analysis in the development and refinement of clinical assessment instruments

    Psychological Assessment

    (1995)
  • E.B. Foa et al.

    DSM-IV field trial: Obsessive-compulsive disorder

    American Journal of Psychiatry

    (1995)
  • Cited by (0)

    View full text